The unexpected formation of a dihydroisobenzofuran derivative from the addition of a Grignard reagent to a 1,3-indanedione

Abstract

Despite good literature precedents, the addition of excess 2-biphenylmagnesium bromide to 4,5-dimethoxy-1,3-indanedione, followed by acid work-up, did not give the desired diol precursor to an Organic Molecule of Intrinsic Microporosity. Instead a dihydroisobenzofuran derivative was isolated in moderate yield and its structure characterised fully by single crystal X-ray crystallography. It is suggested that this product is formed by sequential Grignard addition, retro-aldol reaction, a second Grignard addition and acid-mediated formation of the dihydroisobenzofuran ring. © ARKAT-USA, Inc.