Synthesis of 4,4-Disubstituted beta-Lactams by Regiospecific Electrophile- and Silver-Induced Ring Expansion of 2,2-Disubstituted 1-Methoxycyclopropylamines.
2,2-Disubstituted 1-methoxycyclopropylamines underwent regiospecific ring expansion to 1,4,4-trisubstituted 2-azetidinones by N-chlorination with tert-butyl hypochlorite and subsequent rearrangement with silver tetrafluoroborate. Upon thermolysis, 4,4-disubstituted beta-lactams suffer a characteristic ring opening to afford beta,gamma-unsaturated carboxylic amides. The reduction of 1,4,4-trisubstituted 2-azetidinones with lithium aluminum hydride afforded 1,2,2-trisubstituted azetidines.
De Kimpe
Norbert
N
Department of Organic Chemistry, Faculty of Agricultural and Applied Biological Sciences, University of Gent, Coupure Links 653, B-9000 Gent, Belgium.
Abbaspour Tehrani
Kourosch
K
Fonck
Gwendolien
G