钯催化烯丙基取代反应中手性配体的“甲基效应”

In this paper, two types of chiral ligands 1 and 2 containing pyridinyl moiety and oxazolines bridged by a methylene group were investigated in the palladium catalyzed substitution of 1,3 diphenyl 2 propenyl acetate with dimethyl malonate. Ligands 2, which have two methyl groups at the bridged methylene, gave higher enantioselectivities than their unsubstituted analogues 1. This "methyl effect" increased while the substituent on the C 4 in the oxazoline ring was changed from benzyl to tert butyl. Despite of that the "methyl effect" was found in the palladium catalyzed enantioselective allylic substitution, it was obviously significant for assisting rational design of chiral ligands and catalysts in other asymmetric reaction.

医药中间体行业发展动态

1世界医药中间体市场概况及发展趋势 医药中间体：用于药品生产的化学品 1．1全球药品市场回顾 全球医药市场保持了数十年的高速、稳定的发展上世纪90年代成为全球医药产业发展的黄金期，许多产品成为重磅炸弹药物，2004年全球医药市场突破5000亿美元（见图1）。

国内原料药产业动态及发展建议

我国原料药年产量达 5 6万t,是世界第二大原料药生产国。出口量占总产量的 3 0 %～ 40 % ,2 0 0 1年出口额为 19 2亿美元。产量大、劳动力成本低、技术水平不断提高成为我国原料药制造业的优势。在世界原料药生产中心向发展中国家转移的过程中 ,印度将成为我国的主要竞争对手 。