Synthetic transformations of higher terpenoids: XXXII. Synthesis of 16-alkenyl-substituted labdatrienes by oxidative coupling of methyl phlomisoate with alkenes
摘要:
Reactions of methyl phlomisoate with methyl acrylate, phenyl acrylate, methyl vinyl ketone, phenyl vinyl ketone, or N-substituted acrylamides catalyzed by Pd(OAc)(2) in the presence of Cu(OAc)(2), p-benzoquinone in the mixture of propionic acid and acetonitrile proceed regio- and stereoselectively with the formation of (E)-16-vinyl labdatrienoates. The oxidative coupling under these conditions of the methyl phlomisoate with styrene results in a mixture of 15,16-distyryl-, 16-styryl-, and 16-(1-phenylvinyl)-derivatives of furanolabdanoid.