Synthesis of picropodophyllin homolactone

Based on a Wittig olefination strategy, the first synthesis of picropodophyllin homolactone 2 is described in nine steps and 30% overall yield from podophyllotoxine 1. The relative configuration of 2 was unambiguously determined using 2D NOESY NMR and a Monte Carlo search protocol. This work corrects the literature on the synthesis of 2. (C) 2000 Elsevier Science Ltd. All rights reserved.