RESUMO
[reaction: see text] A concise asymmetric synthesis of the tricyclic core of cyathane diterpenes is described, based on a novel transition-metal-catalyzed intramolecular [5 + 2] cycloaddition of ynone-vinylcyclopropane 10 (assembled from commercially available (S)-(-)-limonene), which proceeds in 90% yield with >95% selectivity. This strategy provides efficient access (14 steps and 13% overall yield) to potential analogues as well as precursors of nerve growth factor (NGF)-inducing diterpenes.
Assuntos
Diterpenos/síntese química , Cicloexenos , Diterpenos/química , Diterpenos/farmacologia , Limoneno , Fator de Crescimento Neural/efeitos dos fármacos , Fator de Crescimento Neural/metabolismo , Terpenos/químicaRESUMO
[reaction--see text] This paper describes a catalytic, asymmetric approach to the C(1)(')-C(10)(') segment of pamamycin 621A. We synthesize this segment in a convergent manner, with each of the coupling partners ultimately deriving from enantiomerically enriched methylketene dimer.