TiCl4-mediated aldol reactions of chiral methyl α-silyloxy ketones with a variety of aldehydes provide the corresponding 1,4-syn aldol adducts with moderate to high stereocontrol. This transformation represents a new approach to substrate-controlled acetate aldol reactions and complements the 1,4-anti asymmetric induction produced by the related α-benzyloxy ketones. This new approach could be useful
Enantioselective Total Synthesis of (−)-Incarviatone A
作者:Benke Hong、Chao Li、Zhen Wang、Jie Chen、Houhua Li、Xiaoguang Lei
DOI:10.1021/jacs.5b08551
日期:2015.9.23
We report herein the first totalsynthesis of (-)-incarviatone A (1) in 14 steps starting from commercially available inexpensive phenylacetic acid (9). Our early stage synthesis relies on the scalable and sequential C-H functionalization to rapidly assemble the indanyl dialdehyde framework. Further biomimetic cascade strategy allows us to obtain the natural product in a one-pot operation. We also
Amides derived from pyrrolidine and methyl (S)-lactate, methyl (S)-2-hydroxy-3-phenylpropanoate, or methyl (S)-2-hydroxy-3-methylbutanoate, after O-benzylation and O-silylation have been treated with EtLi or EtMgCl under suitable conditions, to give excellent overall yields of enantiopure ethyl ketones. The chelating ability of alpha-OBn amides (and even of alpha-O-TBS amides, which has been demonstrated by NMR to be better than that of N-OMe amides) accounts for the performance of the approach. (C) 1997 Elsevier Science Ltd.