Premium
Diastereoselective Reductions with Zinc Powder in a Mixture of NaOH aq. and MeOH for Syntheses of (±)‐1,2‐Diarylethylenediamines
Author(s) -
Ando Shin,
Ishizuka Tadao
Publication year - 2018
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201800976
Subject(s) - chemistry , zinc , yield (engineering) , selectivity , selective reduction , base (topology) , organic chemistry , nuclear chemistry , catalysis , mathematical analysis , materials science , mathematics , metallurgy
A practical diastereoselective reduction of spiroisoimidazole to afford rac ‐1,2‐diarylethylenediamines was developed. Zinc was used as a reducing agent in a mixture of basic H 2 O and an alcoholic cosolvent under open air. The choices of NaOH as the base and MeOH as the cosolvent were key factors that heightened selectivity, and under these optimized conditions, the yield of rac ‐1,2‐diphenylethylenediamine (DPEN) was > 11‐fold that of meso isomer. The reaction was amenable to a 0.10 mol scale, which resulted in the isolation of 16.9 g of rac ‐DPEN. Control experiments suggested that the reduction with zinc followed a different pathway from that of a known Birch reduction.