S. Motallebi et P. Muller, RHODIUM(II)-CATALYZED DECOMPOSITION OF BETA,PSI-UNSATURATED DIAZO-COMPOUNDS, Helvetica Chimica Acta, 76(8), 1993, pp. 2803-2813
The Rh(II)-catalyzed decomposition of beta,gamma-unsaturated diazo ket
ones 1 in the presence of MeOH leads via vinylogous Wolff rearrangemen
t to gamma,delta-unsaturated esters 6 (Schemes 1 and 2) A modest asymm
etric induction is achieved when the reaction is carried out with chir
al tetrakis(pyrrolidinecarboxylato)- or tetrakis(oxazolidinonato)dirho
dium(II) complexes. Vinyl and phenyl diazoacetates 11 and 20, respecti
vely, or 1-diazo-3-phenyl-propan-2-one (25), when subjected to the sam
e reaction conditions, react by OH insertion with MeOH 3-5). In the ab
sence of MeOH, phenyl diazoacetates 20 and 25 undergo intramolecular C
H insertion to 22 and 26, respectively. Intramolecular CH insertion oc
curs with N-aryldiazoamides 23 even in the presence of MeOH (Scheme 5)
.