Trapping of carbolithiation-derived tertiary benzylic α-lithio piperidines with carbon electrophiles: Controlling the formation of α-amino quaternary and vicinal stereocenters
作者:Timothy K. Beng、Nathan Fox、Daniel P. Bassler、Amir Alwali、Kayla Sincavage、Ann Wens V. Silaire
DOI:10.1039/c5ob01371b
日期:——
The interception of carbolithiation-derived tertiary benzylic α-lithio piperidines with carbon electrophiles has led to the diastereoselective synthesis of vicinally functionalized piperidines bearing α-amino quaternary stereocenters.
On the Stereochemical Divergence in the Conjugate Addition of Lithium Dimethylcuprate/Trimethylsilyl Chloride to γ-Alkoxy and γ-Ureido α,β-Unsaturated Esters
作者:Stephen Hanessian、Kenzo Sumi
DOI:10.1055/s-1991-28396
日期:——
A comparative study was made of the reaction of chiral non-racemic γ-alkoxy and γ-ureido-α,β-unsaturated esters with lithium dimethylcuprate in the presence of trimethylsilyl chloride. The possible origins of the anti- and syn-additions respectively are discussed and rationalized.
at low temperature, allylic lithium organocuprates and allylic organocopper(I) compounds add stereoselectively (cis-addition) to α-acetylenic esters to afford α,δ-biethylenic esters.
Coupling reactions of epoxide linked to a secondary oxygen group with Gilman reagents were examined. The regiochemical direction depended on whether there is TMS or MOM as a protective group of the secondary alcohol. anti-Epoxy alcohol 6 tended to react with Me2CuLi at the C4 position to generate 1,2-diol 22 as a major component. Epoxide 7 linked to a trimethylsilyloxy group displayed selective formation
Resolution and determination of the absolute stereochemistry of .alpha.- and .beta.-aryl-substituted .gamma.-methylenevalerolactones, alternate substrate inhibitors for serine proteases
作者:Du Jong Baek、Scott B. Daniels、Peter E. Reed、John A. Katzenellenbogen