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Method for synthesizing alkyl olefin through coupling of double-bond carbon-hydrogen bond and saturated carbon-hydrogen bond
The invention discloses a method for synthesizing alkyl olefin through coupling of a double-bond carbon-hydrogen bond and a saturated carbon-hydrogen bond. According to to the method, one-pot reactionis implemented on olefin and sulfoxide in the presence of ferric salt and hydrogen peroxide to generate alkyl olefin; in the method, sulfoxide is simultaneously used as a hydrocarbylation reagent anda solvent of olefin, and a reaction product is alkyl olefin from sulfoxide alkyl coupled with olefin carbon atoms, so that an olefin carbon chain is increased; the reaction conditions are mild, the selectivity is good, the yield is high, and industrial production is facilitated.
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Paragraph 0060-0069; 0090

(2021/02/10)

Organocatalytic epoxidation and allylic oxidation of alkenes by molecular oxygen
Pyrrole-proline diketopiperazine (DKP) acts as an efficient mediator for the reduction of dioxygen by Hantzsch ester under mild conditions to allow the aerobic metal-free epoxidation of electron-rich alkenes. Mechanistic crossovers are underlined, explaining the dual role of Hantzsch ester as a reductant/promoter of the DKP catalyst and a simultaneous competitor for the epoxidation of alkenes when HFIP is used as a solvent. Expansion of this protocol to the synthesis of allylic alcohols was achieved by adding a catalytic amount of selenium dioxide as an additive, revealing a superior method to the classical application of t-BuOOH as a selenium dioxide oxidant.
Orfanidou, Maria,Petsi, Marina,Zografos, Alexandros L.
supporting information
p. 9172 - 9178
(2021/11/30)

Method for hydrocarbylation synthesis of trisubstituted and tetrasubstituted olefins from non-terminal olefins
The invention discloses a method for hydrocarbylation synthesis of trisubstituted and tetrasubstituted olefins from non-terminal olefins, wherein the method comprises the steps: carrying out hydrocarbylation reaction on the non-terminal olefins and sulfoxide in the presence of ferric salt and hydrogen peroxide, carrying out one-pot reaction on disubstituted non-terminal olefins to generate the trisubstituted olefins, and carrying out one-pot reaction on the trisubstituted non-terminal olefins to generate the tetrasubstituted olefins. In the method, sulfoxide is simultaneously used as a hydrocarbylation reagent and a solvent of olefins, and one more hydrocarbyl substituent is added to a reaction product compared with a double-bond carbon atom of a reactant, so that an olefin carbon chain isincreased; the reaction conditions are mild, the selectivity is good, the yield is high, and industrial production is facilitated.
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Paragraph 0054-0063

(2021/02/06)

A Relay Strategy Actuates Pre-Existing Trisubstituted Olefins in Monoterpenoids for Cross-Metathesis with Trisubstituted Alkenes
A retrosynthetic disconnection-reconnection analysis of epoxypolyenes - substrates that can undergo cyclization to podocarpane-type tricycles - reveals relay-actuated Δ6,7-functionalized monoterpenoid alcohols for ruthenium benzylidene catalyzed olefin cross-metathesis with homoprenyl benzenes. Successful implementation of this approach provided several epoxypolyenes as expected (E/Z, ca. 2-3:1). The method is further generalized for the cross-metathesis of pre-existing trisubstituted olefins in other relay-actuated Δ6,7-functionalized monoterpenoid alcohols with various other trisubstituted alkenes to form new trisubstituted olefins. Epoxypolyene cyclization of an enantiomerically pure, but geometrically impure, epoxypolyene substrate provides an enantiomerically pure, trans-fused, podocarpane-type tricycle (from the E-geometrical isomer).
Bahou, Karim A.,Braddock, D. Christopher,Meyer, Adam G.,Savage, G. Paul,Shi, Zhensheng,He, Tianyou
p. 4906 - 4917
(2020/04/10)

Superelectrophilic Fe(III)-Ion Pairs as Stronger Lewis Acid Catalysts for (E)-Selective Intermolecular Carbonyl-Olefin Metathesis
An intermolecular carbonyl-olefin metathesis reaction is described that relies on superelectrophilic Fe(III)-based ion pairs as stronger Lewis acid catalysts. This new catalytic system enables selective access to (E)-olefins as carbonyl-olefin metathesis products. Mechanistic investigations suggest the regioselective formation and stereospecific fragmentation of intermediate oxetanes to be the origin of this selectivity. The optimized conditions are general for a variety of aryl aldehydes and trisubstituted olefins and are demonstrated for 28 examples in up to 64% overall yield.
Albright, Haley,Schindler, Corinna S.,Vonesh, Hannah L.
supporting information
p. 3155 - 3160
(2020/04/21)

Unexpected Nickel Complex Speciation Unlocks Alternative Pathways for the Reactions of Alkyl Halides with dppf-Nickel(0)
The mechanism of the reactions between dppf-Ni0 complexes and alkyl halides has been investigated using kinetic and mechanistic experiments and DFT calculations. The active species is [Ni(κ2-dppf)(κ1-dppf)], which undergoes a halide abstraction reaction with alkyl halides and rapidly captures the alkyl radical that is formed. The rates of the reactions of [Ni(COD)(dppf)] with alkyl halides and the yields of prototypical nickel-catalyzed Kumada cross-coupling reactions of alkyl halides are shown to be significantly improved by the addition of free dppf ligand.
Greaves, Megan E.,Lloyd-Jones, Guy C.,Maseras, Feliu,Nelson, David J.,Ronson, Thomas O.,Sproules, Stephen
p. 10717 - 10725
(2020/11/09)

Cycloneophylpalladium(IV) Complexes: Formation by Oxidative Addition and Selectivity of Their Reductive Elimination Reactions
The cycloneophylpalladium(II) complexes [Pd(CH2CMe2C6H4)(κ2-N,N′-L)] (L = RO(CH2)3N(CH2-2-C5H4N)2, R = H, Me) undergo oxidation to Pd(IV) with bromine or iodine to give [PdX(CH2CMe2C6H4)(κ3-N,N′,N″-L)]X (X = Br, I) or with methyl iodide to give the transient complexes [PdMe(CH2CMe2C6H4)(κ3-N,N′,N″-L)]I. The products of Br2 and I2 oxidation, [PdX(CH2CMe2C6H4)(κ3-N,N′,N″-L)]X (X = Br, I), are sufficiently stable to be isolated, but they decompose slowly in solution by reductive elimination to give the palladium(II) products [PdX(κ3-N,N′,N″-L)]X (X = Br, I). The organic products are formed via either CH2-Ar or CH2-X bond formation. In the latter case, neophyl rearrangement and protonolysis steps follow reductive elimination to give a mixture of organic products. The methylpalladium(IV) complexes [PdMe(CH2CMe2C6H4)(κ3-N,N′,N″-L)]I decompose at 0 °C by selective reductive elimination with Me-Ar bond coupling to give the alkylpalladium(II) complex [Pd(CH2CMe2-2-C6H4Me)(κ3-N,N′,N″-L)]I. The mechanisms of the reactions have been explored by kinetic studies.
Behnia, Ava,Blacquiere, Johanna M.,Fard, Mahmood A.,Puddephatt, Richard J.
p. 4037 - 4050
(2020/12/01)

Silver triflate mediated dehydration of benzylic alcohols and vinyl hydrovinylation of styrene
The use of silver trifluoromethanesulfonate (silver triflate, AgOTf) as a halide abstraction reagent is pervasive in organometallic chemistry. However, recent reports suggest a “hidden” Br?nsted acid lurks within it that may catalyze purported metal-based catalysis. Presented herein are new reactions that are either catalyzed or promoted by the “hidden” acid, generated upon silver triflate degradation. 1-Phenylethanol dehydrates to styrene (1) upon reaction with AgOTf at 90 °C over 24 h, which slowly coverts to the vinyl hydrovinylation product (E)-1,3-diphenyl-1-butene, (2, 64%) over several days. While dehydration was observed with a number of benzylic alcohols to yield Zaitsev selective olefins, only 1-phenylethanol affords vinyl hydrovinylation products. Dehydration was not observed for primary and secondary alcohols, suggesting an acid catalyzed E1elimination reaction mechanism is at play. The degradation of silver triflate was found to be the source of the “hidden” Br?nsted acid, which demonstrated a dependence on the presence of light and oxygen. In the absence of light and oxygen, dehydration of 1-phenylethanol was severely stunted and 2 is not formed, but instead the ether product, oxy-bis(ethane-1,1-diyl)dibenzene (3), is afforded. The mesitylene internal standard also reacts with the in situ formed styrene to produce 2-(1-phenylethyl)mesitylene (4) through acid catalyzed electrophilic aromatic substitution. These reactions were monitored (products characterized) by GC-MS and/or 1H NMR spectroscopic methods. We present herein the details of these reactions and our characterization methods.
Quillian, Brandon,Fields, Alexis E.,Chace, Desiree,Murrell Vickery, Amanda,Sharma, Mrinali,Zurwell, Dane,Bazemore, Joseph G.,Phan, Long,Thomas, Dorey,Padgett, Clifford W.
p. 224 - 229
(2019/03/02)

Action of Organoaluminum Reagents on Esters: Alkene Production and the Degradation of Synthetic Lubricants
Reactions of methylaluminum reagents with ester-based lubricating oils are mimicked through the reaction of trimethylaluminum (TMA) with tetraesters C(CH2OC(O)R)4 (R = C5H11 4Pent, Bn 4Bn). Using a 2:1 stoichiometry gave adduct 4Pent(TMA)4. NMR spectroscopy on 1:1-12:1 TMA/4Pent systems suggested 4Pent gave dimethylated adduct C5H11CMe2OAlMe2(TMA), 2Pent(TMA). Similar combination of TMA with 4Bn at raised temperatures transformed 4Bn into C(CH2OAlMe2)4(2Bn)4 5(2Bn)4 by sequential reaction of each ester group. Doubly reacted {BnC(O)OCH2}2C(CH2OAlMe2)2(2Bn)2 7Bn(2Bn)2 was isolated and characterized. A Mitsubishi molecule could also be isolated, its formation rationalized by the elimination of 2Bn and TMA from 5(2Bn)4. The action of MenAlCl3-n (n = 1, 1.5, 2) was studied initially on monoester BnC(O)OMe 1Bn. Combining excess Me2AlCl with 1Bn gave adduct 1Bn(Me2AlCl) and small amounts of dimethylated BnCMe2OAlMe2(Me2AlCl), 2Bn(Me2AlCl), and MeOAlCl2 10. 2Bn(Me2AlCl) was fully characterized and, in the presence of 10, acted as a source of 2Bn(MeAlCl2). From this species, a mixture of alkenes could be generated by formal elimination of Me3Al2(OH)Cl2 13, the decomposition of which was presumed to also explain MeH observation. Replacing Me2AlCl with aluminum sesquichloride or MeAlCl2 led to progressively more sluggish but similar reactions. Using MenAlCl3-n (n = 1, 1.5, 2) with tetraesters suggested similar reactivity to monoesters.
Slaughter, Jonathan,Molyneux, Samuel A.,Peel, Andrew J.,Wheatley, Andrew E. H.
p. 395 - 408
(2019/01/11)

Cleavage of lignin C-O bonds over a heterogeneous rhenium catalyst through hydrogen transfer reactions
Hydrogenolysis is one of the most popular strategies applied in the depolymerization of lignin for the production of aromatic chemicals. Currently, this strategy is mainly conducted under high hydrogen pressure, which can pose safety risks and is not sustainable and economical. Herein, we reported that heterogeneous rhenium oxide supported on active carbon (ReOx/AC) exhibited excellent activity in the selective cleavage of lignin C-O bonds in isopropanol. High yields of monophenols (up to 99.0%) from various lignin model compounds and aromatic liquid oils (>50%) from lignin feedstock were obtained under mild conditions in the absence of H2. The characterization of the catalyst by X-ray absorption fine structure, X-ray photoelectron spectroscopy and H2-temperature-programed reduction suggested that the activity of ReOx/AC could be attributed to the presence of ReIV-VI. The interaction between the surface oxygen groups of the active carbon and rhenium oxide could also play an important role in the cleavage of the C-O bonds. Notably, an ReOx/AC-catalyzed C-O bond cleavage pathway beyond a typical deoxydehydration mechanism was disclosed. More importantly, 2D-HSQC-NMR and GPC characterizations showed that ReOx/AC exhibited high activity not only in β-O-4 cleavage, but also in the deconstruction of more resistant β-5 and β-β linkages in lignin without destroying the aromatic ring. This study paves the way for the development of rhenium-based catalysts for the controlled reductive valorization of realistic lignin materials through a hydrogen transfer pathway.
Zhang, Bo,Qi, Zaojuan,Li, Xinxin,Ji, Jianwei,Zhang, Leilei,Wang, Hua,Liu, Xiaoyan,Li, Changzhi
supporting information
p. 5556 - 5564
(2019/10/28)

Nucleophilic Substitutions of Alcohols in High Levels of Catalytic Efficiency
A practical method for the nucleophilic substitution (SN) of alcohols furnishing alkyl chlorides, bromides, and iodides under stereochemical inversion in high catalytic efficacy is introduced. The fusion of diethylcyclopropenone as a simple Lewis base organocatalyst and benzoyl chloride as a reagent allows notable turnover numbers up to 100. Moreover, the use of plain acetyl chloride as a stoichiometric promotor in an invertive SN-type transformation is demonstrated for the first time. The operationally straightforward protocol exhibits high levels of stereoselectivity and scalability and tolerates a variety of functional groups.
Stach, Tanja,Dr?ger, Julia,Huy, Peter H.
supporting information
p. 2980 - 2983
(2018/05/28)

A General Catalytic Method for Highly Cost- and Atom-Efficient Nucleophilic Substitutions
A general formamide-catalyzed protocol for the efficient transformation of alcohols into alkyl chlorides, which is promoted by substoichiometric amounts (down to 34 mol %) of inexpensive trichlorotriazine (TCT), is introduced. This is the first example of a TCT-mediated dihydroxychlorination of an OH-containing substrate (e.g., alcohols and carboxylic acids) in which all three chlorine atoms of TCT are transferred to the starting material. The consequently enhanced atom economy facilitates a significantly improved waste balance (E-factors down to 4), cost efficiency, and scalability (>50 g). Furthermore, the current procedure is distinguished by high levels of functional-group compatibility and stereoselectivity, as only weakly acidic cyanuric acid is released as exclusive byproduct. Finally, a one-pot protocol for the preparation of amines, azides, ethers, and sulfides enabled the synthesis of the drug rivastigmine with twofold SN2 inversion, which demonstrates the high practical value of the presented method.
Huy, Peter H.,Filbrich, Isabel
supporting information
p. 7410 - 7416
(2018/04/30)

Carbonyl–Olefin Cross-Metathesis Through a Visible-Light-Induced 1,3-Diol Formation and Fragmentation Sequence
A visible-light-mediated approach to carbonyl–olefin cross-metathesis is described. Photoinduced hole catalysis was used to promote the formation of 1,3-diols from aldehydes and styrenes, which were then readily fragmented under acidic conditions to form the cross-metathesis products. The use of 1,3-diols as intermediates, rather than the energetically more demanding oxetanes, provides a new, orthogonal mechanistic strategy for carbonyl–olefin cross-metathesis. Furthermore, this approach does not require any metals, ligands, or additives, and provides the products with high levels of E selectivity. A mechanistic rationale is provided and supported by both theoretical calculations and experiments. Additionally, a practical synthesis of a new acridinium-based photocatalyst, including full characterization, is presented.
Pitzer, Lena,Sandfort, Frederik,Strieth-Kalthoff, Felix,Glorius, Frank
supporting information
p. 16219 - 16223
(2018/11/23)

Alkene functionalization for the stereospecific synthesis of substituted aziridines by visible-light photoredox catalysis
A novel strategy involving visible-light-induced functionalization of alkenes for the synthesis of substituted aziridines was developed. The readily prepared N-protected 1-aminopyridinium salts were used for the generation of N-centered radicals. This approach allowed the synthesis of aziridines bearing various functional groups with excellent diastereoselectivity under mild conditions. Moreover, this protocol was successfully applied to prepare structurally diverse nitrogen-containing frameworks.
Yu, Wan-Lei,Chen, Jian-Qiang,Wei, Yun-Long,Wang, Zhu-Yin,Xu, Peng-Fei
supporting information
p. 1948 - 1951
(2018/03/01)

CATALYSTS AND METHODS FOR FORMING ALKENYL AND ALKYL SUBSTITUTED ARENES
Embodiments of the present disclosure provide for Rh(I) catalysts, methods of making alkenyl substituted arenes (e.g., allyl arene, vinyl arene, and the like), methods of making alkyl substituted arenes, and the like.
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Paragraph 0157

(2018/03/25)

Selective Cleavage of C?O Bonds in Lignin Catalyzed by Rhenium(VII) Oxide (Re2O7)
The selective cleavage of C?O bonds in typical model lignin β-O-4 compounds and deconstruction of a realistic lignin feedstock catalyzed by Re2O7 is described. High yields of C?O cleavage products (up to 97.8 %) from model compounds and oils (76.3 %) from organosolv pinewood lignin were obtained under mild conditions. Evidence for the pathway of this catalytic process is also provided.
Qi, Zaojuan,Zhang, Bo,Ji, Jianwei,Li, Xinxin,Dai, Tao,Guo, Haiwei,Wang, Aiqin,Lu, Lican,Li, Changzhi
p. 500 - 505
(2018/03/27)

Intermolecular radical addition to carbonyls enabled by visible light photoredox initiated hole catalysislena
Herein, we present a novel strategy for the utilization of simple carbonyl compounds, aldehydes and ketones, as intermolecular radical acceptors. The reaction is enabled by visible light photoredox initiated hole catalysis and the in situ Br?nsted acid activation of the carbonyl compound. This regioselective alkyl radical addition reaction does not require metals, ligands or additives and proceeds with a high degree of atom economy under mild conditions. The proposed mechanism is supported by both experimental and theoretical studies.
Pitzer, Lena,Sandfort, Frederik,Strieth-Kalthoff, Felix,Glorius, Frank
supporting information
p. 13652 - 13655
(2017/11/06)

Toward a mild dehydroformylation using base-metal catalysis
Dehydroformylation, or the reaction of aldehydes to produce alkenes, hydrogen gas, and carbon monoxide, is a powerful transformation that is underdeveloped despite the high industrial importance of the reverse reaction, hydroformylation. Interestingly, nature routinely performs a related transformation, oxidative dehydroformylation, in the biosynthesis of cholesterol and related sterols under mild conditions using base-metal catalysts. In contrast, chemists have recently developed a non-oxidative dehydroformylation method; however, it requires high temperatures and a precious-metal catalyst. Careful study of both approaches has informed our efforts to design a base-metal catalyzed, mild dehydroformylation method that incorporates benefits from each while avoiding several of their respective disadvantages. Importantly, we show that cooperative base metal catalysis presents a powerful, mechanistically unique approach to reactions which are difficult to achieve using conventional catalyst design.
Abrams, Dylan J.,West, Julian G.,Sorensen, Erik J.
p. 1954 - 1959
(2017/03/09)

Promoting Lignin Depolymerization and Restraining the Condensation via an Oxidation-Hydrogenation Strategy
For lignin valorization, simultaneously achieving the efficient cleavage of ether bonds and restraining the condensation of the formed fragments represents a challenge thus far. Herein, we report a two-step oxidation-hydrogenation strategy to achieve this goal. In the oxidation step, the O2/NaNO2/DDQ/NHPI system selectively oxidizes CαH-OH to Cα=O within the β-O-4 structure. In the subsequent hydrogenation step, the α-O-4 and the preoxidized β-O-4 structures are further hydrogenated over a NiMo sulfide catalyst, leading to the cleavage of Cβ-OPh and Cα-OPh bonds. Besides the transformation of lignin model compounds, the yield of phenolic monomers from birch wood is up to 32% by using this two-step strategy. The preoxidation of CαH-OH to Cα=O not only weakens the Cβ-OPh ether bond but also avoids the condensation reactions caused by the presence of Cα+ from dehydroxylation of CαH-OH. Furthermore, the NiMo sulfide prefers to catalyze the hydrogenative cleavage of the Cβ-OPh bond connecting with a Cα=O rather than catalyze the hydrogenation of Cα=O back to the original CαH-OH, which further ensures and utilizes the advantages of preoxidation.
Zhang, Chaofeng,Li, Hongji,Lu, Jianmin,Zhang, Xiaochen,Macarthur, Katherine E.,Heggen, Marc,Wang, Feng
p. 3419 - 3429
(2017/06/09)

Visible-Light-Driven Palladium-Catalyzed Radical Alkylation of C?H Bonds with Unactivated Alkyl Bromides
Reported herein is a novel visible-light photoredox system with Pd(PPh3)4 as the sole catalyst for the realization of the first direct cross-coupling of C(sp3)?H bonds in N-aryl tetrahydroisoquinolines with unactivated alkyl bromides. Moreover, intra- and intermolecular alkylations of heteroarenes were also developed under mild reaction conditions. A variety of tertiary, secondary, and primary alkyl bromides undergo reaction to generate C(sp3)?C(sp3) and C(sp2)?C(sp3) bonds in moderate to excellent yields. These redox-neutral reactions feature broad substrate scope (>60 examples), good functional-group tolerance, and facile generation of quaternary centers. Mechanistic studies indicate that the simple palladium complex acts as the visible-light photocatalyst and radicals are involved in the process.
Zhou, Wen-Jun,Cao, Guang-Mei,Shen, Guo,Zhu, Xing-Yong,Gui, Yong-Yuan,Ye, Jian-Heng,Sun, Liang,Liao, Li-Li,Li, Jing,Yu, Da-Gang
supporting information
p. 15683 - 15687
(2017/11/16)

Photocatalytic Transfer Hydrogenolysis of Allylic Alcohols on Pd/TiO2: A Shortcut to (S)-(+)-Lavandulol
We report herein a regio- and stereoselective photocatalytic hydrogenolysis of allylic alcohols to form unsaturated hydrocarbons employing a palladium(II)-loaded titanium oxide; the reaction proceeds at room temperature under light irradiation without stoichiometric generation of salt wastes. Olefin and saturated alcohol moieties tolerated the reaction conditions. Hydrogen atoms were selectively incorporated into less sterically congested carbons of the allylic functionalities. This protocol allowed a short-step synthesis of (S)-(+)-lavandulol from (R)-(?)-carvone by avoiding otherwise necessary protection/deprotection steps.
Takada, Yuki,Caner, Joaquim,Kaliyamoorthy, Selvam,Naka, Hiroshi,Saito, Susumu
supporting information
p. 18025 - 18032
(2017/12/08)

Esterase-sensitive sulfur dioxide prodrugs inspired by modified Julia olefination
Sulfur dioxide (SO2) is an endogenously produced gaseous molecule, and is emerging as a potential gasotransmitter. Herein, we describe the first series of esterase-sensitive prodrugs inspired by modified Julia olefination as SO2 donors.
Wang, Wenyi,Wang, Binghe
supporting information
p. 10124 - 10127
(2017/09/23)

Lewis base-assisted Lewis acid-catalyzed selective alkene formation via alcohol dehydration and synthesis of 2-cinnamyl-1,3-dicarbonyl compounds from 2-aryl-3,4-dihydropyrans
Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often plagued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4-dihydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.
Liu, Changhui,Pan, Bin,Gu, Yanlong
p. 979 - 986
(2016/07/06)

METHOD OF CONVERTING ALCOHOL TO HALIDE
The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
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Page/Page column 50; 144; 148; 149

(2017/01/02)

Copper(I)-Catalyzed Allylic Substitutions with a Hydride Nucleophile
An easily accessible copper(I)/N-heterocyclic carbene (NHC) complex enables a regioselective hydride transfer to allylic bromides, an allylic reduction. The resulting aryl- and alkyl-substituted branched α-olefins, which are valuable building blocks for synthesis, are obtained in good yields and regioselectivity. A commercially available silane, (TMSO)2Si(Me)H, is employed as hydride source. This protocol offers a unified alternative to the established metal-catalyzed allylic substitutions with carbon nucleophiles, as no adaption of the catalyst to the nature of the nucleophile is required.
Nguyen, T. N. Thanh,Thiel, Niklas O.,Pape, Felix,Teichert, Johannes F.
p. 2455 - 2458
(2016/06/09)

Selective Double Carbomagnesiation of Internal Alkynes Catalyzed by Iron-N-Heterocyclic Carbene Complexes: A Convenient Method to Highly Substituted 1,3-Dienyl Magnesium Reagents
Controlled multicarbometalation of alkynes has been envisaged as an efficient synthetic method for dienyl and polyenyl metal reagents, but an effective catalyst enabling the transformation has remained elusive. Herein, we report that an iron(II)-N-heterocyclic carbene (NHC) complex (IEt2Me2)2FeCl2 (IEt2Me2 = 1,3-diethyl-4,5-dimethylimidazol-2-ylidene) can serve as a precatalyst for the double carbometalation of internal unsymmetrical alkynes with alkyl Grignard reagents, producing highly substituted 1,3-dienyl magnesium reagents with high regio- and stereoselectivity. Mechanistic studies suggest the involvement of low-coordinate organoiron(II)-NHC species as the in-cycle intermediates. The strong σ-donating nature of IEt2Me2 and its appropriate steric property are thought the key factors endowing the iron-NHC catalyst fine performance.
Liu, Yuesheng,Wang, Lijun,Deng, Liang
supporting information
p. 112 - 115
(2016/01/25)

Deoxygenation of carbonyl compounds using an alcohol as an efficient reducing agent catalyzed by oxo-rhenium complexes
This work describes the first methodology for the deoxygenation of carbonyl compounds using an alcohol as a green solvent/reducing agent catalyzed by oxo-rhenium complexes. The system 3-pentanol/ReOCl3(SMe2)(OPPh3) was successfully employed in the deoxygenation of several aryl ketones to the corresponding alkenes and also in the deoxygenation of aryl aldehydes to alkanes with moderate to excellent yields. The catalyst ReOCl3(SMe2)(OPPh3) can also be used in several catalytic cycles with good activity.
Bernardo, Joana R.,Fernandes, Ana C.
supporting information
p. 2675 - 2681
(2016/05/24)

Iron-Catalyzed Regioselective Oxo- and Hydroxy-Phthalimidation of Styrenes: Access to α-Hydroxyphthalimide Ketones
This paper describes the aerobic oxidation of styrenes catalyzed by iron(III) chloride (FeCl3) to form β-keto-N-alkoxyphthalimides in fair to good yields. This oxidative process employs mild conditions with green and atom efficient dioxygen (O2) as the oxidant.
Zhang, Ji-Zong,Tang, Yu
p. 752 - 764
(2016/03/09)

Facile Protocol for Catalytic Frustrated Lewis Pair Hydrogenation and Reductive Deoxygenation of Ketones and Aldehydes
A series of ketones and aldehydes are reduced in toluene under H2 in the presence of 5 mol % B(C6F5)3 and either cyclodextrin or molecular sieves affording a facile metal-free protocol for reduction to alcohols. Similar treatment of aryl ketones resulted in metal-free deoxygenation yielding aromatic hydrocarbons.
Mahdi, Tayseer,Stephan, Douglas W.
p. 8511 - 8514
(2015/11/27)

Cobalt-Catalyzed Cross-Coupling of Grignards with Allylic and Vinylic Bromides: Use of Sarcosine as a Natural Ligand
Sarcosine was discovered to be an excellent ligand for cobalt-catalyzed carbon-carbon cross-coupling of Grignard reagents with allylic and vinylic bromides. The Co(II)/sarcosine catalytic system is shown to perform efficiently when phenyl and benzyl Grignards are coupled with alkenyl bromides. Notably, previously unachievable Co-catalyzed coupling of allylic bromides with Grignards to linearly coupled α-products was also realized with Co(II)/sarcosine catalyst. This method was used for efficient preparation of the key intermediate in an alternative synthesis of the antihyperglycemic drug sitagliptin.
Frlan, Rok,Sova, Matej,Gobec, Stanislav,Stavber, Gaj,?asar, Zdenko
p. 7803 - 7809
(2015/08/18)

D-Glucosamine in iron-catalysed cross-coupling reactions of Grignards with allylic and vinylic bromides: Application to the synthesis of a key sitagliptin precursor
A sustainable D-glucosamine ligand is successfully introduced into iron-catalysed C-C cross-coupling reactions for the first time. The Fe(acac)2/D-glucosamine·HCl/Et3N catalytic system was effective at 5 mol% loading in coupling reactions of Grignard reagents with organic bromides. Moderate to high efficiency was achieved with preserved stereochemistry when allyl (Csp3) or alkenyl (Csp2) bromides were coupled with phenylmagnesium (Csp2) or benzylmagnesium (Csp3) bromides. The catalytic system developed was also successfully applied for the novel and economic preparation of a Michael-acceptor-like starting material used in an alternative synthesis of the drug sitagliptin, a known blockbuster for the treatment of type II diabetes mellitus.
Sova, Matej,Frlan, Rok,Gobec, Stanislav,Stavber, Gaj,asar, Zdenko
p. 528 - 535
(2015/08/04)

SnCl4-Zn: A novel reductive system for deoxygenative coupling of aliphatic, aromatic, chalcone epoxide, and indanone carbonyl compounds to olefins
SnCl4-Zn complex provided a novel reductive system in the deoxygenative cross-coupling of aliphatic, aromatic, chalcone epoxide and indanone carbonyl compounds to olefins in high yield (55-86%) at reflux temperature in THF. The advantage of this reagent is inexpensive, short reaction time, and high yield compared to the reagents used in the McMurry cross-coupling reaction.
Pathe, Gulab Khushalrao,Ahmed, Naseem
supporting information
p. 1555 - 1561
(2015/03/14)

Graphite oxide activated zeolite NaY: Applications in alcohol dehydration
A mixture of graphite oxide (GO) and the zeolite NaY (Si/Al = 5.1) was used to dehydrate various alcohols to their respective olefinic products. Using conditions optimized for 4-heptanol (15 wt% GO-NaY (1 : 1 wt/wt), 150°C, 30 min), a series of secondary and tertiary aliphatic alcohols were cleanly dehydrated in moderate to excellent conversions (27.5-97.2%). Several primary alcohols were also dehydrated, although higher catalyst loadings (200 wt% GO-NaY (1 : 1) and longer reaction times (3 h) were required. The enhanced dehydration activity was attributed to the ability of GO to convert NaY to an acidic form and without the need for ammonium cation exchange and/or high temperature calcination. The Royal Society of Chemistry 2013.
Todd, Alexander D.,Bielawski, Christopher W.
p. 135 - 139
(2013/03/29)

Solvent-free dehydration of alcohols using LiCI-acidicalumina
Conjugated enynes, dienes and simple olefins have been cleanly and selectively synthesized, good-to-excellent yields, by dehydration of corresponding alcohols using focused microwave irradiation on the surface of LiCI-acidic alumina.
Bagheri Marandi,Pourjavadi,Hosseinzadeh
p. 1141 - 1145
(2013/02/25)

Unique catalysis of gold nanoparticles in the chemoselective hydrogenolysis with H2: Cooperative effect between small gold nanoparticles and a basic support
Gold nanoparticles on hydrotalcite act as a heterogeneous catalyst for the chemoselective hydrogenolysis of various allylic carbonates to the corresponding terminal alkenes using H2 as a clean reductant. The combination of gold nanoparticles and basic supports elicited significantly unique and selective catalysis in the hydrogenolysis.
Noujima, Akifumi,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
p. 6723 - 6725
(2012/07/28)

Facile η5-η3 hapticity interconversion in pentamethylcyclopentadienyl ruthenium(ii) complexes containing a phenylmethallyl ("open indenyl") ligand
The indenyl effect has been introduced to pentadienyl ("open cyclopentadienyl") chemistry by preparation of the phenylmethallyl ("open indenyl") ligand oIndMe. The reaction of its potassium salt K(oIndMe) with [(η5-C 5Me5)RuCl]4 afforded the sandwich complex [(η5-C5Me5)Ru(η5-oInd Me)] (1), which, upon treatment with PMe3, CO, and 2,6-dimethylphenyl isocyanide (CN-o-Xy), easily underwent η5- η3 hapticity interconversion and formed the complexes [(η5-C5Me5)Ru(η3-oInd Me)(L)] (2, L = PMe3; 3, L = CO; 4, L = CN-o-Xy). In these complexes, the η3-bound phenylmethallyl ligand adopts an anti-conformation with regard to the relative positions of the phenyl and methyl substituents. For the PMe3 complex anti-2, slow conversion to the syn-isomer was observed, and this equilibrium reaction was monitored by NMR spectroscopy at 50 °C to determine a first order rate constant of k 323 K = 6.57 × 10-6 (± 0.02 × 10 -6) s-1 and an activation barrier of ΔG° = 26.8 kcal mol-1. DFT calculations afforded a stabilization of syn-2 and syn-3 by ΔG298 = -1.54 and -1.74 kcal mol-1 over the respective anti-isomer.
Gloeckner, Andreas,Arias, Oscar,Bannenberg, Thomas,Daniliuc, Constantin G.,Jones, Peter G.,Tamm, Matthias
scheme or table
p. 11511 - 11518
(2012/01/04)

Determining the enantioselectivity of chiral catalysts by mass spectrometric screening of their racemic forms
The enantioselectivity of a chiral catalyst can be determined from its racemic form by mass spectrometric screening of a nonequal mixture of two mass-labeled quasienantiomeric substrates. The presented method opens up new possibilities for evaluating catalyst structures that are not readily available in enantiomerically pure form.
Ebner, Christian,Mueller, Constanze A.,Markert, Christian,Pfaltz, Andreas
supporting information; experimental part
p. 4710 - 4713
(2011/06/17)

Catalytic dehydration of benzylic alcohols to styrenes by rhenium complexes
The oxygen content of biomass-based materials can be reduced by selective dehydration of hydroxyl groups. As a first step towards biomass-based chemicals, rhenium-based catalysts are shown to be active in the dehydration of various benzylic alcohols to styrene moieties. The turnover frequencies are superior to the benchmark catalyst sulfuric acid, without sacrificing any selectivity.
Korstanje, Ties J.,Jastrzebski, Johann T. B. H.,Gebbink, Robertus J. M. Klein
experimental part
p. 695 - 697
(2011/12/15)

Evidence of hydrogen migration in an alkylphenyldiazirine excited state
(Figure Presented) Ultrafast photolysis (350 nm) of alkylphenyldiazirines promotes the diazirine to the S1 excited state. Solvent and substituent effects on the excited state lifetimes indicate that the S 1 state is highly polarized and undergoes a [1,2]-H shift in concert with nitrogen extrusion in cyclohexane.
Zhang, Yunlong,Kubicki, Jacek,Platz, Matthew S.
supporting information; experimental part
p. 3182 - 3184
(2010/09/16)

Aromatic cation activation of alcohols: Conversion to alkyl chlorides using dichlorodiphenylcyclopropene
(Chemical Equation Presented) A novel paradigm for the activation of alcohols toward nucleophilic displacement via formation of cyclopropenium ethers is described. The conversion of a range of alcohol substrates to the corresponding alkyl chlorides occurs rapidly upon treatment with 3,3-dichloro-1,2-diphenylcyclopropene. 1H NMR data support the intermediacy of a cyclopropenium intermediate, and the reaction is demonstrated to proceed primarily via the SN2 mechanism for 1-phenylethanol. A total of 12 examples of substrate scope are provided.
Kelly, Brendan D.,Lambert, Tristan H.
supporting information; experimental part
p. 13930 - 13931
(2009/12/25)

Titanocene-promoted intermolecular couplings of epoxides with nitriles. An easy access to β-hydroxyketones
(Chemical Equation Presented) Radical couplings of epoxides and nitriles mediated by Cp2TiCl provide a diastereoselective route to the synthesis of β-hydroxyketones. The conditions of this "aldol- like" reaction are mild enough to avoid the dehydration of the β-hydroxyketone. The scope of the coupling reaction with functionalized and tetrasubstituted epoxides has been studied. The radical character of the coupling reactions is demonstrated.
Fernandez-Mateos,Encinas Madrazo,Herrero Teijon,Rubio Gonzalez
supporting information; experimental part
p. 3913 - 3918
(2009/10/20)

o-benzenedisulfonimide as a soft, efficient, and recyclable catalyst for the acylation of alcohols, phenols, and thiols under solvent-free conditions: Advantages and limitations
o-Benzenedisulfonimide turns out to be a highly efficient Bransted acid catalyst for the acylation of a number of alcohols, phenols, and thiols under a metal- and solvent-free procedure; reaction conditions are mild and yields very good. After the workup, the catalyst can be easily recovered and purified, ready to be reused, with economic and ecological advantages. Georg Thieme Verlag Stuttgart · New York.
Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano,Venturello, Paolo
scheme or table
p. 3625 - 3632
(2009/07/04)

A highly selective, high-speed, and hydrolysis-free O-acylation in subcritical water in the absence of a catalyst
(Chemical Equation Presented) Fast and furious: A wide range of alcohols are acylated by acetic anhydride, in the absence of catalyst, in subcritical water in a flow-type microreaction system. The esters are selectively produced in high yields at temperatures of 200 to 250°C. Varying the amount of acetic anhydride added with respect to the alcohols allows the regioselective acylation of one or both hydroxy groups of various dihydroxy compounds (see picture).
Sato, Masahiro,Matsushima, Keiichiro,Kawanami, Hajime,Ikuhsima, Yutaka
p. 6284 - 6288
(2008/04/05)

Phenyl versus alkyl migration in the fragmentation of alkoxychlorocarbenes
Phenyl versus methyl (alkyl) group migration is assessed in the fragmentations of neophyloxychlorocarbene, 2,2-diphenylpropyloxychlorocarbene, and 1-phenylcyclopropylmethoxychlorocarbene. Rate constants and activation parameters of the fragmentations are also reported.
Moss, Robert A.,Fu, Xiaolin
p. 235 - 237
(2007/10/03)

Iodine induced transformations of alcohols under solvent-free conditions
Iodine has been shown to be an efficient catalyst for transformations of alcohols under solvent-free conditions. In the presence of 5% of iodine, tertiary alcohols underwent dehydration forming the corresponding alkenes, while in the case of 2-phenylpropane-2-ol cyclodimerisation to 1,1,3-trimethyl-3-phenylindane took place. Secondary and primary benzyl alcohols under the same conditions gave the corresponding ethers.
Stavber, Gaj,Zupan, Marko,Stavber, Stojan
p. 8463 - 8466
(2007/10/03)

Widely applicable Pd-catalyzed trans-selective monoalkylation of unactivated 1,1-dichloro-1-alkenes and Pd-catalyzed second substitution for the selective synthesis of E or Z trisubstituted alkenes
(Chemical Equation Presented) Double substitution: The first selective and widely applicable method for a step-wise alkylation of 1,1-dichloro-1-alkenes involving a cross-coupling double substitution using Pd-catalysis has been developed. This method provides an efficient and highly selective route for the synthesis of E or Z trisubstituted alkenes. dpephos = bis(o- diphenylphosphanylphenylether).
Tan, Ze,Negishi, Ei-Ichi
p. 762 - 765
(2007/10/03)

Synthesis of enantiopure 2-amino-1-phenyl and 2-amino-2-phenyl ethanols using enantioselective enzymatic epoxidation and regio- and diastereoselective chemical aminolysis
Several enantiopure 1,2-amino alcohols have been prepared by combining a stereoselective enzymatic epoxidation of styrenes with regio- and stereoselective chemical reactions. An interesting reactivity has been noted concerning the reaction of epoxides and NH3 under microwave activation.
Sello, Guido,Orsini, Fulvia,Bernasconi, Silvana,Gennaro, Patrizia Di
p. 372 - 376
(2007/10/03)

A facile synthesis of (tert-alkoxy)amines
Tertiary alcohols react with stoichiometric BF3?Et 2O and N-hydroxyphthalimide to yield N-alkoxyphthalimides. Subsequent hydrazinolyses afford the title compounds.
Palandoken, Hasan,Bocian, Chris M.,McCombs, Michelle R.,Nantz, Michael H.
p. 6667 - 6669
(2007/10/03)

Palladium catalyzed Suzuki-Miyaura coupling with aryl chlorides using a bulky phenanthryl N-heterocyclic carbene ligand
A novel bis-phenanthryl N-heterocyclic carbene (NHC) based palladium acetate catalyst was effective for the coupling of various aryl and vinyl chlorides with organoboron compounds. N,N-Bis-(2,9-dicyclohexyl-10-phenanthryl)- 4,5-dihydroimidazolium chloride 8 (H2ICP·HCl) with Pd(OAc)2 and KF·18-c-6 in THF at room temperature gave Suzuki-Miyaura coupling of aryl and vinyl chorides, including unactivated and di-ortho substituted substrates in high yields. Hindered tri- and tetra-ortho substituted products were also efficiently produced. Benzyl chloride was also found to be a useful coupling partner and trimethylboroxine was used to give methylated products. The effect of ligand, base, temperature, solvent, and reaction time are reported along with various substrates including halides and triflates.
Song, Chun,Ma, Yudao,Chai, Qiang,Ma, Chanqin,Jiang, Wei,Andrus, Merritt B.
p. 7438 - 7446
(2007/10/03)

Generation of magnesium carbenoids from 1-chloroalkyl phenyl sulfoxides with a Grignard reagent and applications to alkylation and olefin synthesis
Treatment of 1-chloroalkyl phenyl sulfoxides with a Grignard reagent at low temperature gave magnesium carbenoids in quantitative yields. The generated magnesium carbenoids were found to be stable at lower than -60°C for long periods of time and are reactive with Grignard reagents to give alkylated products. The reaction of the generated magnesium carbenoids with various kinds of lithium α-sulfonyl carbanions gave olefins with carbon-carbon bond-formation in good to high yields. This method offers a good way for the preparation of olefins. The scope and limitations of the above-mentioned reactions are described.
Satoh, Tsuyoshi,Kondo, Atsushi,Musashi, Jun
p. 5453 - 5460
(2007/10/03)