Allylation of erythromycin derivatives: introduction of allyl substituents into highly hindered alcohols.

Functionalized erythromycin 9-oxime derivatives are 6-O-allylated under mild conditions using substituted allyl tert-butyl carbonates under palladium(0) catalysis. This allylation works well where traditional ether-forming protocols function poorly. Allyl tert-butyl carbonates provide higher yields in this reaction than lesser substituted carbonates such as ethyl or isopropyl. Aryl-substituted allyl carbonates or carbamates may be employed as well and, when used, produce trans-olefinic products.