Abstract
Antidepressant drug (R)-rolipram was readily prepared on a large scale from isovanilline via a succinct route. The key reaction was carried out using a 1 mol% loading of nickel(II)-bis[(S,S)-N,N′-dibenzylcyclohexane-1,2-diamine]Br2 complex as the catalyst. The ee% could reach to 99%, and the catalyst could be recovered and used in the next reaction cycle with high ee%.
GRAPHICAL ABSTRACT
Notes
a All the reactions stopped with conversion of more than 99%.
b Isolated yield.
c Enantiomeric excess was determined by HPLC with chiracel AD column.
d Neat reaction with 1.5 equivalent of diethyl malonate.
a Isolated yield.
b Enantiomeric excess was determined by HPLC with chiracel AD column.