Rh. Woudenberg et al., STRUCTURE OF A DIELS-ALDER ADDUCT AT A 5,7-DISUBSTITUTED THEBAINE DERIVATIVE, Acta crystallographica. Section C, Crystal structure communications, 50, 1994, pp. 913-915
The structure of (+)-ethyl oxy-6beta,14beta-ethenomorphinan-8beta-carb
oxylate (3), C25H31NO5, is described. Diels-Alder reaction of the theb
aine analogoue (-)-5beta-methyl-7-methoxy-6-demethoxythebaine (2), wit
h ethyl propenoate gives rise to anomalous alpha-face approach of the
dienophile, yielding the title compound (3), in which the etheno bridg
e is at the 6beta,14beta position and the ethoxycarbonyl substituent i
s at the 8beta position.