Highly Enantioselective Synthesis of γ-Hydroxy-α,β-acetylenic Esters Catalyzed by a β-Sulfonamide Alcohol
作者:Li Lin、Xianxing Jiang、Weixia Liu、Li Qiu、Zhaoqing Xu、Jiangke Xu、Albert S. C. Chan、Rui Wang
DOI:10.1021/ol070692x
日期:2007.6.1
concerns the asymmetric addition of methyl propiolate to aldehydes with 1,2-dimethoxyethane (DME) as additive and beta-sulfonamide alcohol titanium complex as a catalyst. The reactions proceeded under mild conditions and gave the highly functionalized chiral propargylic alcohols with high ee values and good yields. Differences between three types of ligands have also been discussed.
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。
Reactivity of γ-Hydroxy-α,β-acetylenic Esters with Amines: Facile Synthesis of the Optically Active 4-Amino-2(5<i>H</i>)-furanones
作者:Li-Hong Zhou、Xiao-Qi Yu、Lin Pu
DOI:10.1021/jo802592h
日期:2009.3.6
A convenient synthesis of the optically active 4-amino-2(5H)-furanones is discovered by combining an asymmetric alkyne addition to aldehydes and a subsequent aliphatic amine addition. Both steps can be conducted at room temperature and the products are obtained with high enantioselectivity (84−90% ee). The 4-amino-2(5H)-furanones are also found to undergo very facile electrophilic substitution reactions
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.