Rh-Catalyzed Cyclization of 3-Aryloxycarbonyldiazonaphthoquinones for the Synthesis of beta-Phenylnaphthalene Lactones and Formal Synthesis of Pradimicinone

摘要

In this study, we developed a novel method for the synthesis of beta-phenylnaphthalene lactones. The diazo-transfer reactions of 2-azido-1,3-dimethylimidazolinium chlorides to 3-aryloxycarbonyl-1-naphthols proceeded smoothly to give corresponding 3-aryloxycarbonyldiazonaphthoquinones in high yields. These intermediates were further transformed to beta-phenylnaphthalene lactones through a Rh-catalyzed intramolecular formal C-H insertion reaction. This method of lactone formation was efficiently applied to the formal total synthesis of pradimicinone.