- Complex Polyheterocycles and the Stereochemical Reassignment of Pileamartine A via Aza-Heck Triggered Aryl C-H Functionalization Cascades
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Structurally complex benzo- and spiro-fused N-polyheterocycles can be accessed via intramolecular Pd(0)-catalyzed alkene 1,2-aminoarylation reactions. The method uses N-(pentafluorobenzoyloxy)carbamates as the initiating motif, and this allows aza-Heck-type alkene amino-palladation in advance of C-H palladation of the aromatic component. The chemistry is showcased in the first total synthesis of the complex alkaloid (+)-pileamartine A, which has resulted in the reassignment of its absolute stereochemistry.
- Bower, John F.,Caiger, Lewis,García-Cárceles, Javier,Hazelden, Ian R.,Jones, Benjamin T.,Langer, Thomas,Lewis, Richard J.
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supporting information
p. 15593 - 15598
(2021/10/12)
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- Chemodivergent Synthesis of One-Carbon-Extended Alcohols via Copper-Catalyzed Hydroxymethylation of Alkynes with Formic Acid
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The development of selective catalytic reactions that utilize easily available reagents for the efficient synthesis of alcohols is a long-standing goal of chemical research. Here an intriguing strategy for the chemodivergent copper-catalyzed hydroxymethylation of alkynes with formic acid and hydrosilane has been developed. By simply tuning the amount of formic acid and reaction temperature, distinct one-carbon-extended primary alcohols, that is, allylic alcohols and β-branched alkyl alcohols, were produced with high levels of Z/E-, regio-, and enantioselectivity.
- Jin, Xin,Fu, Hong-Chen,Wang, Mei-Yan,Huang, Shouying,Wang, Yue,He, Liang-Nian,Ma, Xinbin
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supporting information
p. 4997 - 5001
(2021/06/28)
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- Magnesium chloride (MgCl2) catalyzed highly regioselective C-3 ring opening of 2,3 epoxy alcohols by N-nucleophile
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We herein report Magnesium chloride (MgCl2) catalyzed first highly C3-selective ring-opening reaction of various 2,3-epoxy alcohols with assorted N-Nucleophiles and sodium azide to furnish 3-amino-1,2 diols and 3-azido-1,2 diols respectively in high yields under mild reaction conditions. This protocol attributes the use of catalytic amount of Magnesium chloride (MgCl2), simple reaction conditions, practical operation and broad functional group tolerance.
- Kumar, Amit,Panda, Gautam
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- Copper-Catalyzed and Proton-Directed Selective Hydroxymethylation of Alkynes with CO2
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An intriguing strategy for copper-catalyzed hydroxymethylation of alkynes with CO2 and hydrosilane was developed. Switched on/off a proton source, for example, tBuOH, direct hydroxymethylation and reductive hydroxymethylation could be triggered selectively, delivering a series of allylic alcohols and homobenzylic alcohols, respectively, with high levels of Z/E, regio- and enantioselectivity. Such a selective synthesis is attributed to the differences in response of vinylcopper intermediate to proton and CO2. The protonation of vinylcopper species is demonstrated to be prior to hydroxymethylation, thus allowing a diversion from direct alkyne hydroxymethylation to reductive hydroxymethylation in the presence of suitable proton.
- Wang, Mei-Yan,Jin, Xin,Wang, Xiaofei,Xia, Shumei,Wang, Yue,Huang, Shouying,Li, Ying,He, Liang-Nian,Ma, Xinbin
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supporting information
p. 3984 - 3988
(2020/12/25)
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- Highly-functionalized arene synthesis based on palladium on carbon-catalyzed aqueous dehydrogenation of cyclohexadienes and cyclohexenes
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Transition metal-catalyzed dehydrogenation is a clean oxidation method requiring no additional oxidants. We have accomplished a heterogeneous Pd/C-catalyzed aqueous dehydrogenation of 1,4-cyclohexadienes and cyclohexenes to give the corresponding highly-functionalized arenes. Furthermore, various arenes could be efficiently constructed in a one-pot manner via a Diels-Alder reaction and the following dehydrogenation.
- Yasukawa, Naoki,Yokoyama, Hiroki,Masuda, Masahiro,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 1213 - 1217
(2018/03/28)
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- Ni-Catalyzed regio- and stereoselective addition of arylboronic acids to terminal alkynes with a directing group tether
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Addition of arylboronic acids to directing group tethered acetylenes in a regio and stereoselective manner using an inexpensive catalytic system is achieved for the first time to access highly sought after allyl/homoallyl alcohol/amine units. The apparent vinylnickel intermediate was successfully trapped by the Michael electrophiles to get defined tri- and tetra-substituted olefins. An interesting selectivity switch was observed with internal alkynes.
- Hari Babu, Madala,Ranjith Kumar, Gadi,Kant, Ruchir,Sridhar Reddy, Maddi
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supporting information
p. 3894 - 3897
(2017/04/04)
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- Systematic methodology for the development of biocatalytic hydrogen-borrowing cascades: Application to the synthesis of chiral α-substituted carboxylic acids from α-substituted α,β-unsaturated aldehydes
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Ene-reductases (ERs) are flavin dependent enzymes that catalyze the asymmetric reduction of activated carbon-carbon double bonds. In particular, α,β-unsaturated carbonyl compounds (e.g. enals and enones) as well as nitroalkenes are rapidly reduced. Conversely, α,β-unsaturated esters are poorly accepted substrates whereas free carboxylic acids are not converted at all. The only exceptions are α,β-unsaturated diacids, diesters as well as esters bearing an electron-withdrawing group in α- or β-position. Here, we present an alternative approach that has a general applicability for directly obtaining diverse chiral α-substituted carboxylic acids. This approach combines two enzyme classes, namely ERs and aldehyde dehydrogenases (Ald-DHs), in a concurrent reductive-oxidative biocatalytic cascade. This strategy has several advantages as the starting material is an α-substituted α,β-unsaturated aldehyde, a class of compounds extremely reactive for the reduction of the alkene moiety. Furthermore no external hydride source from a sacrificial substrate (e.g. glucose, formate) is required since the hydride for the first reductive step is liberated in the second oxidative step. Such a process is defined as a hydrogen-borrowing cascade. This methodology has wide applicability as it was successfully applied to the synthesis of chiral substituted hydrocinnamic acids, aliphatic acids, heterocycles and even acetylated amino acids with elevated yield, chemo- and stereo-selectivity. A systematic methodology for optimizing the hydrogen-borrowing two-enzyme synthesis of α-chiral substituted carboxylic acids was developed. This systematic methodology has general applicability for the development of diverse hydrogen-borrowing processes that possess the highest atom efficiency and the lowest environmental impact. This journal is
- Knaus, Tanja,Mutti, Francesco G.,Humphreys, Luke D.,Turner, Nicholas J.,Scrutton, Nigel S.
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p. 223 - 233
(2015/02/19)
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- Asymmetric epoxidation of allylic alcohols catalyzed by vanadium-binaphthylbishydroxamic acid complex
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A vanadium-binaphthylbishydroxamic acid (BBHA) complex-catalyzed asymmetric epoxidation of allylic alcohols is described. The optically active binaphthyl-based ligands BBHA 2a and 2b were synthesized from (S)-1,1'-binaphthyl-2,2'dicarboxylic acid and N-substituted-O-trimethylsilyl (TMS)-protected hydroxylamines via a one-pot, three-step procedure. The epoxidations of 2,3,3-trisubstituted allylic alcohols using the vanadium complex of 2a were easily performed in toluene with a TBHP water solution to afford (2R)-epoxy alcohols in good to excellent enantioselectivities.
- Noji, Masahiro,Kobayashi, Toshihiro,Uechi, Yuria,Kikuchi, Asami,Kondo, Hisako,Sugiyama, Shigeo,Ishii, Keitaro
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p. 3203 - 3210
(2015/03/30)
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- Highly enantioselective hydrogenation of 2-substituted-2-alkenols catalysed by a ChenPhos-Rh complex
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Highly enantioselective hydrogenation of a variety of 2-substituted-2- alkenols has been achieved using a ChenPhos-Rh complex as catalyst, giving ≥99% ee for most substrates. Optically active antifungal agent amorolfine was first synthesised using hydrogenation as the key step. This journal is
- Wang, Quanjun,Liu, Xueying,Liu, Xian,Li, Bin,Nie, Huifang,Zhang, Shengyong,Chen, Weiping
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supporting information
p. 978 - 980
(2014/01/06)
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- Copper-catalyzed hydrocarboxylation of alkynes using carbon dioxide and hydrosilanes
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Getting a fix: The copper-catalyzed hydrocarboxylation of alkynes using carbon dioxide in the presence of a hydrosilane, which serves as a reducing agent, has been developed (see scheme). Copper fluorides bearing N-heterocyclic carbene ligands such as IMes and Cl2IPr show high catalytic activities.
- Fujihara, Tetsuaki,Xu, Tinghua,Semba, Kazuhiko,Terao, Jun,Tsuji, Yasushi
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p. 523 - 527
(2011/03/16)
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- Divergent regioselectivity in the synthesis of trisubstituted allylic alcohols by nickel- and ruthenium-catalyzed alkyne hydrohydroxymethylation with formaldehyde
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Stoichiometric metals banned: Nonsymmetrically disubstituted alkynes were converted into primary trisubstituted allylic alcohols upon exposure to paraformaldehyde in the presence of nickel or ruthenium catalysts, which exhibit complementary regioselectivity and complete stereoselectivity in the absence of exogenous reducing agents (see scheme). Copyright
- Bausch, Cory C.,Patman, Ryan L.,Breit, Bernhard,Krische, Michael J.
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supporting information; experimental part
p. 5687 - 5690
(2011/08/06)
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- An organocatalytic asymmetric nazarov cyclization
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An organocatalytic asymmetric Nazarov cyclization of diketoesters that proceeds by means of a dual activation mechanism has been developed. Screening of a number of catalysts led to a new thiourea that incorporates a primary amino group. The method gives rise to cyclic products with two adjacent quaternary asymmetric carbon atoms, one of which is an all-carbon stereocenter, with complete or nearly complete diastereoselectivity and in high or very high enantiomeric excess. A brief and very convenient synthesis of the acyclic diketoester starting materials through nucleophilic addition to a ketene is also described.
- Basak, Ashok K.,Shimada, Naoyuki,Bow, William F.,Vicic, David A.,Tius, Marcus A.
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supporting information; experimental part
p. 8266 - 8267
(2010/08/04)
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- Stereospecific Stille-coupling reaction of (Z)-1,2- bis(trimethylstannyl)ethenes with hypervalent iodonium salts
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The Stille coupling of (Z)-1,2-bis(trimethylstannyl)ethenes with hypervalent iodonium salts (1 equiv) proceeded stereospecifically in the presence of PdCl2 (5 mol %) in DMF at room temperature to afford partially substituted (Z)-vinylstannanes under mild conditions. Alternatively, the use of 2 equivalents of hypervalent iodonium salts afforded tri-substituted alkenes.
- Kang, Suk-Ku,Lee, Yong-Tack,Lee, Sang-Ho
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p. 3573 - 3576
(2007/10/03)
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- Asymmetric catalysis. Production of chiral diols by enantioselective catalytic intramolecular hydrosilation of olefins
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Rhodium(I) chiral diphosphine complexes efficiently and rapidly catalyze the intramolecular hydrosilation of silyl ethers derived from allylic alcohols. The efficiency and rates of intramolecular hydrosilations were determined for a variety of silyl and olefin substituents. The catalysts were found to tolerate a wide variety of silyl substituents, although terminal alkyl olefin substituents were found to retard catalysis. Terminal aryl olefin substituents were found to be hydrosilated efficiently and at reasonable rates. One of the chiral catalysts is highly enantioselective for terminal aryl olefin substituents. Almost quantitative ee's are obtained. Moreover, the ee's are only slightly sensitive to aryl and olefin substituents, suggesting that this enantioselective catalysis can provide a wide range of chiral species. Oxidative cleavage of the hydrosilation products gives chiral diols.
- Bergens, Steven H.,Noheda, Pedro,Whelan, John,Bosnich
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p. 2121 - 2128
(2007/10/02)
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- One Pot Synthesis of p-Polyphenyls via the Intramolecular Cyclization of 3-Dimethylaminohex-5-en-1-ynes
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Para linked polyphenyls of various molecular weights are conveniently synthesized from p-bis(3-dimethylamino-1-propynyl)arenes and 1-aryl-2-propenyl bromides in moderate yields using a three step, one-pot procedure.
- Unroe, Marilyn R.,Reinhardt, Bruce A.
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p. 981 - 986
(2007/10/02)
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- Reaction of HCo(CO)4 with Methyl 2,3-Diphenyl-2-cyclopropene-1-carboxylate: Synthesis of Methyl t,t-2,3-Diphenyl-c-2-formylcyclopropane-r-1-carboxylate
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Reaction of HCo(CO)4 with the diphenylcyclopropene 1 leads to the three possible hydrogenated cyclopropanes but in addition a single hydroformylation product is formed.This aldehyde was synthesized by an unambiguous procedure; it is compound 2, formed by
- Nalesnik, Theodore E.,Fish, John G.,Horgan, Steven W.,Orchin, Milton
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p. 1987 - 1990
(2007/10/02)
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