Conjugate Boration of β,β-Disubstituted Unsaturated Esters: Asymmetric Synthesis of Functionalized Chiral Tertiary Organoboronic Esters
作者:Xinhui Feng、Jaesook Yun
DOI:10.1002/chem.201002361
日期:2010.12.10
Challenging tertiaryorganoboronicesters containing a β‐ester group were prepared enantioselectively via the asymmetricconjugateboration of β,β‐disubstituted α,β‐unsaturatedesters with a copper–phosphine catalyst (see scheme). The functionalized organoboron derivatives can be utilized as a carbon nucleophile to form all‐carbon quaternary centers.
Reformatskyreagent derived from tert-butyl α-bromoacetate adds to carbonyl compounds in the presence of chiral amino alcohols leading to β-hydroxy tert-butyl esters with good e.e. The enantioface differentiation depends on the reaction conditions and on the structure of the chiral auxiliary. The best chemical yields and e.e. are obtained for aromatic aldehydes by using the C-2 symmetrical chiral bis-amino
Enantioselective reformatsky reaction with ketones. Asymmetric synthesis of β-(tert-hydroxy)esters
作者:Kenso Soai、Atsushi Oshio、Takaki Saito
DOI:10.1039/c39930000811
日期:——
Optically active β-(tert-hydroxy)esters with good enantiomeric excesses (up to 75% e.e.) are synthesised via enantioselective Reformatskyreaction with ketones in the presence of chiral N,N-dialkylnorephedrine.