- A Total Synthesis of (-)-Hamigeran B and (-)-4-Bromohamigeran B
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A concise synthesis of (-)-hamigeran B and (-)-4-bromohamigeran B is presented. The key reactions include a Suzuki coupling of enol triflate 15 with arylboronic ester for efficient synthesis of the densely 1,2,3-trisubstituted cyclopentene 23, a coordinat
- Cao, Bao-Chen,Wu, Guo-Jie,Yu, Fang,He, Yu-Peng,Han, Fu-She
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- Synthesis of quaternary-carbon-containing and functionalized enantiopure pentanecarboxylic acids from biocatalytic desymmetrization of meso-cyclopentane-1,3-dicarboxamides
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Catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase-amidase containing microbial whole-cell catalyst under mild conditions, enantioselective desymmetrizations of meso-cyclopentane-1,3-dicarbonitriles and cyclopentane-1,3-dicarboxamides were studied. Although the nitrile hydratase was found to exhibit high enzymatic activity, but low 1R enantioselectivity toward dinitriles, a number of 2,2-unsymmetrically substituted meso-cyclopentane-1,3-dicarboxamide substrates were converted by the 1S enantioselective amidase into quaternary carbon-bearing enantiopure (1S,2R,3R)-3-carbamoylcyclopentanecarboxylic acids in yields up to 94%. The application of the method was demonstrated by convenient and practical transformations of the resulting (1S,2R,3R)-2-allyl-3-carbamoylcyclopentanecarboxylic acid derivatives into functionalized cyclopentane-fused δ-lactam and δ-lactone compounds.
- Ao, Yu-Fei,Wang, De-Xian,Zhao, Liang,Wang, Mei-Xiang
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- Synthetic Studies on Enantioselective Total Synthesis of Cyathane Diterpenoids: Cyrneines A and B, Glaucopine C, and (+)-Allocyathin B2
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The details for the synthetic studies on enantioselective total synthesis of cyathane diterpenoids cyrneine A (1) and B (2), glaucopine C (3), and (+)-allocyathin B2 are presented. We established a mild Suzuki coupling for heavily substituted n
- Wu, Guo-Jie,Zhang, Yuan-He,Tan, Dong-Xing,He, Long,Cao, Bao-Chen,He, Yu-Peng,Han, Fu-She
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- First Enantioselective Catalytic Wittig Reaction
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Herein we present the first catalytic enantioselective Wittig reaction. Chiral mono- and diphosphines were employed as catalysts for the desymmetrization of a prochiral ketone. The reaction was performed under microwave dielectric heating as well as under conventional heating. Selected catalysts led to moderate to good yields and enantioselectivities. In the presence of (+)-1,2-bis[(2S,5S)-2,5-dimethylphospholano]benzene [(S,S)-Me-DuPhos], an enantiomeric excess of up to 90 % was obtained.
- Werner, Thomas,Hoffmann, Marcel,Deshmukh, Sunetra
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- Desymmetric enantioselective reduction of cyclic 1,3-diketones catalyzed by a recyclable p-chiral phosphinamide organocatalyst
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The P-stereogenic phosphinamides are a structurally novel skeletal class which has not been investigated as chiral organocatalysts. However, chiral cyclic 3-hydroxy ketones are widely used as building blocks in the synthesis of natural products and bioactive compounds. However, general and practical methods for the synthesis of such chiral compounds remain underdeveloped. Herein, we demonstrate that the P-stereogenic phosphinamides are powerful organocatalysts for the desymmetric enantioselective reduction of cyclic 1,3-diketones, providing a useful method for the synthesis of chiral cyclic 3-hydroxy ketones. The protocol displays a broad substrate scope that is amenable to a series of cyclic 2,2-disubstituted five- and six-membered 1,3-diketones. The chiral cyclic 3-hydroxy ketone products bearing an all-carbon chiral quaternary center could be obtained with high enantioselectivities (up to 98% ee) and diastereoselectivities (up to 99:1 dr). Most importantly, the reactions could be practically performed on the gram scale and the catalysts could be reused without compromising the catalytic efficiency. Mechanistic studies revealed that an intermediate formed from P-stereogenic phosphinamide and catecholborane is the real catalytically active species. The results disclosed herein bode well for designing and developing other reactions using P-stereogenic phosphinamides as new organocatalysts.
- Qin, Xu-Long,Li, Ang,Han, Fu-She
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supporting information
p. 2994 - 3002
(2021/03/01)
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- Convenient preparation of synthetically useful chiral quaternary carbon-containing bicyclic compounds with organocatalysts
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Chiral quaternary carbon-containing bicyclic compounds possessing carbonyl functionalities were efficiently synthesized through asymmetric intramolecular aldol reactions with organocatalysts. Bicyclo [3.3.0] and [3.4.0] systems were constructed with a dia
- Kawamoto, Yuichiro,Noguchi, Naoki,Ozone, Daiki,Kobayashi, Toyoharu,Ito, Hisanaka
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supporting information
(2021/11/01)
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- Chiral Phosphoric Acid Catalyzed Desymmetrization of Cyclopentendiones via Friedel–Crafts Conjugate Addition of Indolizines
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An organocatalytic highly diastero- and enantioselective Friedel–Crafts conjugate addition of indolizines to prochiral cyclopentenediones has been successfully developed. This desymmetric transformation provides a direct access to the desired indolizine-substituted cyclopentanediones in yields of 62–91% and excellent stereoselectivities. The utility of the approach was demonstrated by diverse late-stage functionalizations through reduction or oxidation. Importantly, the direct sp2 C–H functionalization with nitromethane in one-pot process resulted in the indolizine-linked axially chiral styrene bearing a remote chiral center.
- Ni, Qijian,Zhu, Zhiming,Fan, Yanjun,Chen, Xiaoyun,Song, Xiaoxiao
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supporting information
p. 9548 - 9553
(2021/12/14)
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- Stereoselective Reduction of Prochiral Cyclic 1,3-Diketones Using Different Biocatalysts
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We have developed biocatalytic methods for the stereoselective reduction of cyclic prochiral 1,3-diketones for the production of optically active β-hydroxyketones and/or 1,3-diols. The recombinant ketoreductase KRED1-Pglu (formulated as purified catalyst)
- Contente, Martina Letizia,Dall’Oglio, Federica,Annunziata, Francesca,Molinari, Francesco,Rabuffetti, Marco,Romano, Diego,Tamborini, Lucia,Rother, D?rte,Pinto, Andrea
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p. 1176 - 1185
(2019/11/16)
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- Enantio- and Diastereoselective Synthesis of Functionalized Carbocycles by Cu-Catalyzed Borylative Cyclization of Alkynes with Ketones
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A single-pot Cu-catalyzed enantio- and diastereoselective tandem hydroboration/borylative cyclization of alkynes with ketones for the synthesis of carbocycles is reported. The reaction proceeds via desymmetrization and generates four contiguous stereocent
- Zanghi, Joseph M.,Liu, Shuang,Meek, Simon J.
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supporting information
p. 5172 - 5177
(2019/07/03)
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- Regio- and Stereoselective Syntheses of 7-Oxabicyclo[2.2.1]heptanes via a Gold(I)-Catalyzed Cycloisomerization of Alkynediols: Asymmetric Total Synthesis of Farnesiferol C
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A highly regio- and stereoselective method to construct a broad range of 7-oxabicyclo[2.2.1]heptanes, which proceeds through a sequential reaction involving gold(I)-catalyzed cycloisomerization of alkynediols and sequential semi-pinacol-type 1,2-alkyl migration, was developed. The developed chemistry was applied to the asymmetric total synthesis of the natural product farnesiferol C.
- Gu, Yue-Qing,Zhang, Peng-Peng,Fu, Jun-Kai,Liu, Song,Lan, Yu,Gong, Jian-Xian,Yang, Zhen
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supporting information
p. 1392 - 1397
(2016/05/19)
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- Palladium nanoparticles bonded to two-dimensional iron oxide graphene nanosheets: A synergistic and highly reusable catalyst for the Tsuji-Trost reaction in water and air
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Low cost, high activity and selectivity, convenient separation, and increased reusability are the main requirements for noble-metal-nanocatalyst- catalyzed reactions. Despite tremendous efforts, developing noble-metal nanocatalysts to meet the above requirements remains a significant challenge. Here we present a general strategy for the preparation of strongly coupled Fe3O4 and palladium nanoparticles (PdNPs) to graphene sheets by employing polyethyleneimine as the coupling linker. Transmission electron microscopic images show that Pd and Fe3O4 nanoparticles are highly dispersed on the graphene surface, and the mean particle size of Pd is around 3 nm. This nanocatalyst exhibits synergistic catalysis by Pd nanoparticles supported on reduced graphene oxide (rGO) and a tertiary amine of polyethyleneimine (Pd/Fe3O4/PEI/rGO) for the Tsuji-Trost reaction in water and air. For example, the reaction of ethyl acetoacetate with allyl ethyl carbonate afforded the allylated product in more than 99% isolated yield, and the turnover frequency reached 2200 h-1. The yield of allylated products was 66% for Pd/rGO without polyethyleneimine. The catalyst could be readily recycled by a magnet and reused more than 30 times without appreciable loss of activity. In addition, only about 7.5% of Pd species leached off after 20 cycles, thus rendering this catalyst safer for the environment. Picking up speed: A multifunctional Pd nanocatalyst was synthesized by in situ growth of palladium nanoparticles (PdNPs) and the assembly of Fe3O4 NPs on reduced graphene oxide (rGO) by employing polyethyleneimine as the coupling linker. This nanocatalyst exhibits synergistic catalysis by the amine on the same rGO surface as the PdNPs for acceleration of the Tsuji-Trost reaction in water and air (see figure).
- Liu, Jian,Huo, Xing,Li, Tianrong,Yang, Zhengyin,Xi, Pinxian,Wang, Zhiyi,Wang, Baodui
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p. 11549 - 11555
(2014/11/07)
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- An easy route toward enantio-enriched polycyclic derivatives via an asymmetric domino conjugate reduction-aldol cyclization catalyzed by a chiral Cu(I) complex
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A highly efficient reductive-aldol cyclization mediated by a chiral Cu(I) complex and an organosilane yielded to cyclic or polycyclic derivatives. An excellent control of the selectivities was reached in most cases (dr up to 100:0 and ee up to 95%). After
- Deschamp, Julia,Hermant, Thomas,Riant, Olivier
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experimental part
p. 3457 - 3467
(2012/06/16)
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- Ruthenium catalyzed selective regio-and-mono-allylation of cyclic 1,3-diketones using allyl alcohols as substrates
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The new ruthenium-sulfonate catalyst Ru(Cp*) (η3-C3H5)(p-CH3C 6H4SO3)2, (Cp*= pentamethylcyclopentadienyl), rapidly and regioselectively mono-all
- Gruber, Stefan,Pregosin, Paul S.
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experimental part
p. 3235 - 3242
(2010/04/28)
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- Efficient construction of polycyclic derivatives via a highly selective cui-catalyzed domino reductive-aldol cyclization
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A versatile methodology for the diastereo-and enantioselective domino reductive-aldol cyclizations is reported. By using a copper (l)/diphosphane ligand, various five-and six-membered rings were generated with good to excellent diastereo-and enantioselect
- Deschamp, Julia,Riant, Olivier
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supporting information; experimental part
p. 1217 - 1220
(2009/10/02)
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- B-alkylcatecholborane-mediated tandem radical conjugated addition-aldol cyclization
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Image Presented A one-pot procedure involving radical conjugate addition of B-alkylcatecholboranes to enones followed by intramolecular aldol reaction is reported. Application to the stereoselective synthesis of monocyclic and bicyclic products with up to
- Beauseigneur, Alice,Ericsson, Cecilia,Renaud, Philippe,Schenk, Kurt
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supporting information; experimental part
p. 3778 - 3781
(2011/02/28)
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- Dioxime oxalates; new iminyl radical precursors for syntheses of N-heterocycles
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Symmetrical and unsymmetrical dioxime oxalates were prepared by treatment of oximes with oxalyl chloride. UV photolysis of these precursors was found to be an atom-efficient way of generating iminyl radicals. The process was most efficient for dioxime oxalates having aryl substituents attached to their C{double bond, long}N bonds. The method was useful for EPR spectroscopic study of iminyl and iminoxyl radicals. Photolyses in toluene solution, of dioxime oxalates containing alkenyl acceptor groups, yielded unsaturated iminyl radicals that ring closed to afford 3,4-dihydro-2H-pyrroles in good yields. Dioxime oxalates with biphenyl substituents also released iminyl radicals that ring closed onto the aromatic acceptor groups and, in acetonitrile solution, this approach provided a useful and atom-efficient method of making substituted phenanthridines.
- Portela-Cubillo, Fernando,Lymer, James,Scanlan, Eoin M.,Scott, Jackie S.,Walton, John C.
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supporting information; experimental part
p. 11908 - 11916
(2009/04/06)
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- Concise access to indolizidine and pyrroloazepine skeleta via intramolecular Schmidt reactions of azido 1,3-diketones
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Readily prepared 2-alkyl-2-azidopropylcycloalkyl-1,3-diones undergo intramolecular Schmidt rearrangement with a range of hard Lewis acids, leading to indolizidinediones and pyrroloazepinediones. Chiral aluminium-based Lewis acids could also be used to mediate this symmetry-breaking transformation, but no significant asymmetric induction was observed. The Royal Society of Chemistry 2006.
- Lertpibulpanya, Duanpen,Marsden, Stephen P.
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p. 3498 - 3504
(2008/09/16)
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- C- vs O-alkylation of 1,3-dicarbonyl compounds using microwave irradiation
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The study of alkylation behaviour of 1,3-dicarbonyl compounds has been carried out with microwave radiation exposure of approximately 2 min resulting in moderate to good yields of the products.
- Nayyar, Sandeep,Trehan, Inderraj,Kaur, Jasamrit
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p. 2342 - 2345
(2007/10/03)
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- Activation of C-O and C-N Bonds in Allylic Alcohols and Amines by Palladium Complexes Promoted by CO2. Synthetic Applications to Allylation of Nucleophiles, Carbonylation, and Allylamine Disproportionation
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The direct activation of the C-O bonds in allylic alcohols catalyzed by palladium complexes has been accelerated by carrying out the reactions under CO2. On reaction with diethylamine, allyl alcohol can be converted into N,N-diethylallylamine in the presence of palladium complexes at room temperature under normal pressure of carbon dioxide. Allylation of various carbon nucleophiles such as β-keto esters and β-diketones can be achieved by using allylic alcohols directly in the presence of palladium complexes and CO2. Direct carbonylation of allylic alcohols into unsaturated carboxylic acids can be catalyzed by palladium complexes under the pressure of CO and CO2. Disproportionation of diallylamine into triallylamine and allylamine is also catalyzed by palladium complexes in the presence of CO2. On the basis of studies on the behavior of η3-allylpalladium hydrogencarbonate complexes with the nucleophiles, mechanisms are proposed to account for the palladium-catalyzed allylation processes influenced by CO2.
- Sakamoto, Masato,Shimizu, Isao,Yamamoto, Akio
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p. 1065 - 1078
(2007/10/03)
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- A new candidate for a properly substituted CD ring component of vitamin D3 via intramolecular asymmetric olefination of a 1,3-cyclopentanedione derivative
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A highly diastereoselective synthesis of hydrindenone derivative 5 (98% de) was achieved via diastereotopic differentiation of 1,3-cyclopentanedione derivative 4 by intramolecular Horner-Emmons olefination. In addition, the compound 5 was converted to ketone 2, a new building block for 1α,25-dihydroxyvitamin D3 (1).
- Mandai,Kaihara,Tsuji
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p. 5847 - 5849
(2007/10/02)
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- Tetraphenylstibonium Methoxide Promoting C-Alkylation of 2-Substituted Cyclic 1,3-Diketones
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Selective C-alkylation of 2-methyl-1,3-cyclopentanedione and 2-methyl-1,3-cyclohexanedione was performed by using tetraphenylstibonium methoxide (Ph4SbOMe).The presence of a substituent at the 2-position was essential for C-alkylation.
- Fujiwara, Masahiro,Hitomi, Kazuhisa,Baba, Akio,Matsuda, Haruo
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p. 875 - 876
(2007/10/02)
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- Alkylation of cyclic 1,3-diketones
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A simple procedure for the C-alkylation of cyclic 1,3-diketones have been reported using Triton B as base in aqueous conditions.
- Rajamannar,Palani,Balasubramanian
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p. 3095 - 3108
(2007/10/02)
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- C-ALLYLATION OF CYCLIC β-DIKETONES IN AN ACIDIC MEDIUM WITH CATALYSIS BY Pd(0)
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A method is proposed for the C-alkylation of cyclic β-diketones by allyl acetate in a weakly acidic medium with Pd(PPh3)4 as catalyst.The method makes it possible to obtain high yields of the corresponding mono- and diallylated products.
- Lapitskaya, M. A.,Pivnitskii, K. K.
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p. 1665 - 1668
(2007/10/02)
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- Asymmetric Microbial Reduction of Prochiral 2,2-Disubstituted Cycloalkanediones
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Asymmetric microbial reduction of a series of 2,2-disubstituted 1,3-cycloalkanediones with bakers' yeast was examined as an example of an enzyme-catalyzed distinction of a substrate containing two trigonal carbonyl centers with stereoheterotropic faces an
- Brooks, Dee W.,Mazdiyasni, Hormoz,Grothaus, Paul G.
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p. 3223 - 3232
(2007/10/02)
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- A New Synthesis of 2,2-Disubstituted Cyclopentane-1,3-diones from Succinic Anhydride
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Reaction of succinic anhydride (1) with (1-ethoxycarbonylethylidene)triphenylphosphorane (2) gives ethyl 2-(5-oxotetrahydrofur-2-ylidene)propanoate 3.Compound 3 is cleaved with sodium ethoxide to the β-ketodiester anion, which is treated with alkylhalide
- Doyle, I. D.,Massy-Westropp, R. A.,Warren, R. F. O.
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p. 845 - 847
(2007/10/02)
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- Prostaglandins and Prostaglandin Intermediates. XV Synthesis of 4-Oxo Carboxylic Acids and γ-Lactones by Oxidative Cleavage of Homoallyl and Homopropargyl Ketones or Alcohols
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A convenient method to convert homoallyl or homopropargyl ketones or alcohols into 4-oxo carboxylic acids or γ-lactones is the oxidative cleavage of the multiple bond with potassium permanganate in diluted sulfuric acid.This is exemplified by the preparation of intermediates for the synthesis of 8-methylprostaglandin C2.The oxidation of the allylic compounds with permanganate is compared with the oxidative cleavage by ozone/hydrogen peroxide, ozone/chromic acid or sodium periodate/potassium permanganate.
- Schick, H.,Welzel, H.-P.,Schwarz, S.,Truckenbrodt, G.
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- Cumulated Ylides, XVII. Synthesis of Cyclic Compounds from Triphenylphosphorane and Oxocarboxylic Acids - A Novel Method for Anellation
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By entropically supported intramolecular Wittig reaction from α-keto carboxylic acids 23 with triphenylphosphorane (1) N-phenylmaleinisoimides 26 and -imides 29 are formed.The compounds 26 can be rearranged into 29 with a catalytic amount of sodium azide. - From γ-keto carboxylic acids 30 3-substituted 2-cyclopenten-1-ones 37 can be derived via the 3,6-dioxo-2-(triphenylphosphoranylidene)alkananilides 33.Analogously, 3-substituted 2-cyclohexen-1-ones 49 are formed from δ-keto carboxylic acids 46. o-Acylbenzoic acids 38, in the case R = H, are converted with 1 into the benzazepinedione derivative 44, and in the case R unlike H into 3-substituted 1-oxo-1H-indene-2-carboxanilides 45. - Starting from oxo carboxylic acids, possessing the carbonyl function in a ring, five- and six-membered rings can be anellated in a simple way.
- Bestmann, Hans Juergen,Schade, Gerold,Luetke, Harry,Moenius, Thomas
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p. 2640 - 2658
(2007/10/02)
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- 2,2-DISUBSTITUIERTE CYCLOPENTAN-1,3-DIONE-21. UNTERSUCHUNG DER REGIOSELEKTIVITAET VON ALKYLIERUNGSREAKTIONEN AN 2-METHYL-CYCLOPENTAN-1,3-DION
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The regioselectivity of the alkylation of alkali metal salts of 2-methyl-cyclopentane-1,3-dione with alkyl halides depends significantly on the structure of the alkylating reagent and the type of solvent used in the reaction.Unsubstituted saturated primar
- Schick, Hans,Schwarz, Hartmut,Finger, Angelika,Schwarz, Sigfrid
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p. 1279 - 1283
(2007/10/02)
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- Chiral Cyclopentanoid Synthetic Intermediates via Asymmetric Microbial Reduction of Prochiral 2,2-Disubstituted Cyclopentanediones
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A prochiral distinction by microbial reduction of 2-propyl- (1), 2-allyl- (4), and 2-propynyl-2-methyl-1,3-cyclopentanedione (7) with bakers' yeast provides efficient access to several chiral cyclopentanoid synthetic intermediates.A short enantioselective
- Brooks, Dee W.,Grothaus, Paul G.,Irwin, William L.
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p. 2820 - 2821
(2007/10/02)
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