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A Highly Efficient and Practical New Allylboronate Tartramide for the Asymmetric Allylboration of Achiral Aldehydes
Author(s) -
Chen Wansuo,
Liu Yanzhu,
Chen Zhirong
Publication year - 2005
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200400670
Subject(s) - chemistry , benzaldehyde , yield (engineering) , enantiomer , enantiomeric excess , recrystallization (geology) , organic chemistry , aldehyde , reaction conditions , medicinal chemistry , enantioselective synthesis , catalysis , paleontology , materials science , metallurgy , biology
Chiral homoallylic alcohols can be prepared from aldehydes upon reaction with two optically pure allylboronatetartramides. The enantiomeric excess is 10–15 % higher for the allylation of benzaldehyde when using N , N ' ‐dibenzyl‐tartramide auxiliary 5b than when using N , N ' ‐diphenyl‐tartramide ( 5a ). 2‐Allyl‐ N , N ' ‐dibenzyl‐1,3,2‐dioxaborolane‐4,5‐dicarbamide ( 2b ) affords homoallylic alcohols with 90–99 % ee upon reaction with some representative aldehydes. The derivatised chiral auxiliaries can be recovered by simple recrystallization, in 85 % yield, without any loss of specific rotation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)