Zinc(II)-Catalyzed Mannich-type Reactions of Hydrazones with Difluoroenoxysilane and Its Application in the Synthesis of Optically Active 2,2-Difluoro-3-oxo-benzohydrazide
作者:Zhiliang Yuan、Yin Wei、Min Shi
DOI:10.1002/cjoc.201090289
日期:2010.9
Zn(OTf)2, Mannich‐type reactions of various aromatic hydrazones 1 with difluoroenoxysilane 2 proceeded smoothly to produce 2,2‐difluoro‐3‐oxo‐benzohydrazides in 27% –78% yields in THF or DCM under mild conditions. An unexpected monofluorination of hydrazone 1m with difluoroenoxysilane 2 was also disclosed in this paper. The first example of the asymmetric Mannich‐type reaction of hydrazone 1a with difluoroenoxysilane
用Zn的催化作用(OTF)2,各种芳族腙的曼尼希型反应1与difluoroenoxysilane 2顺利进行,以产生2,2-二氟-3-氧代- benzohydrazides在27%-78%的收率在THF或DCM中在温和的情况。本文还公开了unexpected 1m与二氟环氧乙烷2的意外单氟化。reported 1a与手性膦-恶唑啉配体的二氟乙氧基硅烷2不对称曼尼希型反应的第一个例子已有报道,在温和条件下,加合物3a具有良好的收率和中等的对映选择性。