Total Synthesis of (+)-Nivetetracyclate A

A stereoselective synthetic approach to the natural product (+)-nivetetracyclate A is reported. The tetracyclic skeleton was assembled in a convergent manner by an alkylation to a diarylmethane and subsequent Friedel-Crafts acylation. Further key steps are an asymmetric Sharpless epoxidation and the boron trifluoride-mediated diastereoselective rearrangement of an epoxy alcohol to a beta-hydroxy aldehyde. Optimized timing for the deprotection step and the chemo- and stereoselective Noyori-transfer hydrogenation of a 1,4-diketone allowed the late stage introduction of the C4 stereocenter.