Enantioselective Mannich-Type Reactions Using a Novel Chiral Zirconium Catalyst for the Synthesis of Optically Active β-Amino Acid Derivatives
作者:Haruro Ishitani、Masaharu Ueno、Shū Kobayashi
DOI:10.1021/ja001642p
日期:2000.8.1
Catalytic enantioselective Mannich-type reactions of silyl enol ethers with aldimines have been successfully performed using a novel chiral zirconium catalyst prepared from zirconium(IV) tert-butoxide (Zr(OtBu)4), 2 equiv of (R)-6,6‘-dibromo-1,1‘-bi-2-naphthol ((R)-6,6‘-Br2BINOL), and N-methylimidazole. The use of aldimines having N-substituted hydroxyphenyl moieties is essential for obtaining high
使用由锆 (IV) 叔丁醇 (Zr(OtBu)4)、2 当量 (R)-6,6' 制备的新型手性锆催化剂,已成功进行甲硅烷基烯醇醚与醛亚胺的催化对映选择性曼尼希型反应-dibromo-1,1'-bi-2-naphthol ((R)-6,6'-Br2BINOL) 和 N-甲基咪唑。使用具有 N-取代羟基苯基部分的醛亚胺对于获得高选择性至关重要,并且 N-取代基团通过氧化裂解转化为游离胺。由芳香醛以及杂环醛和脂肪醛衍生的醛亚胺与甲硅烷基烯醇醚顺利反应,以高产率和高对映选择性得到相应的β-氨基酸衍生物。已经进行了几次 NMR 实验以阐明手性 Zr 催化剂的结构以及这种不对称反应的催化循环。最后,制备了一种新的BINOL衍生物,(R)-6,6'-双(三氟甲基)-1,1'-bi-2-萘酚((R)-6,6'-(CF3)2BINOL) . 原来是秀...