Oxidative carbocation formation in macrocycles: Synthesis of the neopeltolide macrocycle

Abstract

Macrocyclic oxocarbenium ions can be formed from macrolactones that contain benzylic or allylic ether groups through oxidative carbon-hydrogen-bond activation mediated by 2,3-dichloro-4,5-dicyanoquinone (DDQ). The applicability of this efficient reaction to complex-molecule synthesis was demonstrated by its use in a brief formal synthesis of neopeltolide (see retrosynthetic scheme) to form the tetrahydropyrone ring. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.