Asymmetric Reduction of Aromatic Ketones. I. Enantioselective Synthesis of Denopamine.
作者:Takayuki KAWAGUCHI、Kunio SAITO、Kenji MATSUKI、Takeo IWAKUMA、Mikio TAKEDA
DOI:10.1248/cpb.41.639
日期:——
Asymmetric reduction of the N-protected amino ketone (2) with serveral chiral reducing agents, i.e., (R)-(+)-2-amino-3-methyl-1, 1-diphenylbutanol (6)-borane complex (method A), (S, S')-N, N'-dibenzoylcystine (7)-LiBH4-ROH complex (method B), and sodium (S)-prolinate-borane complex (8) (method C), was investigated in an attempt to synthesize denopamine (1) enantioselectively. Reduction of 2f by method B in tetrahydrofuran at 2-3°C gave the best result (88% ee with 95% chemical yield).
用几种手性还原剂不对称还原 N 保护氨基酮 (2),即(R)-(+)-2-amino-3-methyl-1, 1-diphenylbutanol (6)-borane complex (method A),(S, S')-N, N'-dibenzoylcystine (7)-LiBH4-ROH complex (method B),以及 (S)-prolinate-borane complex (8) sodium (method C)。方法 B 在 2-3°C 的四氢呋喃中还原 2f,结果最好(ee 为 88%,化学收率为 95%)。