Synthesis of isochromanones and benzoxepinones by palladium catalyzed cyclocarbonylation reactions

Abstract

Heterocyclic compounds such as lactones, lactams or pyrrolidinones are employed as useful intermediates for the synthesis of biologically active products. In the past decades various preparation routes to these class of heterocycles have been described and palladium-based compounds have been regarded as the most efficient catalysts for the preparation of important cyclic compounds. In this work, novel isochromanome and benzoxepinone derivatives have been prepared and fully characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies and gas chromatography–mass spectrometry (GC–MS) analysis. An effective homogeneous catalytic system based on palladium complex was used. Isochromanone and benzoxepinone derivatives have been synthesized through selective cyclocarbonylation reactions respectively of 2-vinylbenzylalcohols and 2-alkynylbenzylalcohols under syn-gas condition using Pd(OAc)2-dppb as the catalytic system. Depending on the subtrate, different lactone structures were obtained with a good selectivity for each reaction.