- Direct Synthesis of Chiral NH Lactams via Ru-Catalyzed Asymmetric Reductive Amination/Cyclization Cascade of Keto Acids/Esters
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Lactams with a stereogenic center adjacent to the N atom have existed in many medicinal agents and bioactive alkaloids. Herein we report a broadly applicable synthesis of enantioenriched NH lactams through a one-pot asymmetric reductive amination/cyclization sequence of easily available keto acids/esters. Such cascade processes alleviate the demand for protecting group manipulations as well as intermediate purification. This strategy is capable of constructing enantioenriched lactams and benzo-lactams of a five-, six-, or seven-membered ring in generally high yield and with excellent enantioselectivities (up to 97% ee). Scalable and concise syntheses of key drug intermediates have further displayed the importance of this methodology.
- Shi, Yongjie,Tan, Xuefeng,Gao, Shuang,Zhang, Yao,Wang, Jingxin,Zhang, Xumu,Yin, Qin
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supporting information
p. 2707 - 2713
(2020/03/30)
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- Synthesis of 1,4-Keto Esters and 1,4-Diketones via Palladium-Catalyzed Acylation of Siloxycyclopropanes. Synthetic and Mechanistic Studies
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The reaction of a variety of siloxycyclopropanes with acid chlorides in the presence of a catalytic amount of a palladium/phosphine complex gives 1,4-dicarbonyl compounds to good yield. 1-Alkoxy-1-(trialkylsiloxy)-cyclopropanes react with both aromatic and aliphatic acid chlorides in chloroform to give 1,4-keto esters.Synthesis of 1,4-diketones by the acylation of 1-alkyl- or 1-aryl-1-siloxycyclopropanes has been achieved by carrying out the reaction if HMPA under 10-20 atm of carbon monoxide.Kinetic studies and product analysis revealed the unique mechanism of this reaction, which involves rate-determining cleavage of the strained cyclopropane carbon-carbon bond with a coordinatively unsaturated acylpalladium chloride complex.Ab initio calculations of hydroxylated cyclopropane model compounds showed that the unique reactivities of the siloxycyclopropanes may be correlated with the molecular orbital properties of these compounds rather than their ground-state structural properties.
- Fujimura, Tsutomu,Aoki, Satoshi,Nakamura, Eiichi
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p. 2809 - 2821
(2007/10/02)
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- Palladium- and platinum-catalyzed reaction of siloxycyclopropanes with acid chlorides. A homoenolate route to 1,4-dicarbonyl compounds
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1,4-Keto esters and 1,4-diketones have been synthesized by the palladium-catalyzed reaction of siloxycylopropanes and acid chlorides.
- Aoki,Fujimura,Nakamura,Kuwajima
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p. 6541 - 6544
(2007/10/02)
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- Carbon-Carbon Bond-Forming Reactions of Zinc Homoenolate of Esters. A Novel Three-Carbon Nucleophile with General Synthetic Utility
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In the presence of suitable catalysts and additives, the zinc homoenolate of alkyl propionate and its congeners undergo a variety of carbon-carbon bond-forming reactions, e.g., addition onto carbonyl compounds, allylation, arylation, vinylation, and acylation, to produce diverse kinds of alkanoates and cyclopropane derivatives.The moderately reactive zinc homoenolate exhibited a very high degree of chemoselectivity in these reactions.Me3SiCl has been found to greatly accelerate 1,2- or 1,4-addition and the allylation reaction of the zinc reagent.
- Nakamura, Eiichi,Aoki, Satoshi,Sekiya, Kouichi,Oshino, Hiroji,Kuwajima, Isao
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p. 8056 - 8066
(2007/10/02)
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- PALLADIUM CATALYZED REACTIONS OF PROPIONATE HOMOENOLATE. ARYLATION, VINYLATION, AND ACYLATION
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Zinc homoanolate of alkyl propionate undergoes clean C-C bond forming reactions with aryl, vinyl and acid halides in the presence of a palladium catalyst.
- Nakamura, Eiichi,Kuwajima, Isao
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