Asymmetric Synthesis of γ-Hydroxy-α,β-acetylenic Esters Catalyzed by Oxazolidine-Titanium Complex
作者:Jincheng Mao、Jun Guo
DOI:10.1055/s-0029-1217712
日期:2009.9
An efficient catalytic system has been developed for the enantioselective reaction of alkynoates with aromatic aldehydes for the synthesis of optically active γ-hydroxy-α,β-acetylenicesters (with up to 81 % isolated yield and up to 84% enantioselectivity).
Synthesis of a C1 symmetric BINOL–terpyridine ligand and highly enantioselective methyl propiolate addition to aromatic aldehydes
作者:Xi Chen、Wei Chen、Li Wang、Xiao-Qi Yu、De-Shun Huang、Lin Pu
DOI:10.1016/j.tet.2010.01.058
日期:2010.3
catalyze the highlyenantioselective reaction (up to 98% ee) of methyl propiolate with a variety of aromatic aldehydes at 0 °C to give the synthetically useful γ-hydroxy-α,β-acetylenicesters. In comparison with the previously reported BINOL system, the use of (R)-5 requires a reduced amount of the chiral ligand without the addition of a Lewis base. It shows higher enantioselectivity for a number of
合成了一种新型的C 1对称BINOL-叔吡啶配体(R)-5。发现该配体与ZnEt 2和Ti(O i Pr)4结合可在0°C催化丙酸甲酯与各种芳香醛的高度对映选择性反应(最高ee达98%ee),从而得到可合成使用的γ-羟基-α,β-炔属酯。与先前报道的BINOL系统相比,(R)-5的使用需要减少量的手性配体而不添加路易斯碱。对于许多底物,它显示出更高的对映选择性。
Highly enantioselective addition of methyl propiolate to aldehydes catalyzed by a titanium(IV) complex of a β-hydroxy amide
Three chiral beta-hydroxy amide ligands were prepared by the reaction of benzyl chloride with amino alcohols derived from L-tyrosine. The titanium(IV) complex of chiral ligand 4a was found to be an effective catalyst for the asymmetric addition of methyl propiolate, to aliphatic and aromatic aldehydes. The gamma-hydroxy-alpha,beta-acetylenic esters were obtained in excellent enantiomeric excesses (up to 94% ee) under optimized conditions. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.