Manganese triacetate oxidative lactonisation of electron-rich stilbenes possessing catechol and resorcinol substitution (resveratrol analogues)

Treatment of 3,5-dimethoxy-12-benzyloxystilbene 10a or 3,4-dimethoxy-12-benzyloxystilbene 10b with Mn(OAc)3 in acetic anhydride containing 13% acetic acid produced the lactones 4-(4′-benzyloxyphenyl)-5-(3′,5′-dimethoxyphenyl)-furan-2-one 11a and 4-(4-benzyloxyphenyl)-5-(3′,4′-dimethoxyphenyl)-furan-2-one 13 in yields of 35% as a 3:1 diastereomeric mixture (but as one regioisomer) and 13% as a mixture of regioisomers (1:1), respectively.