A Single-Step Synthesis of Symmetrical 1,3-Diarylisobenzofurans

Abstract

A convenient single-step synthesis of various symmetrically substituted 1,3-diarylisobenzofurans from readily available 3-methoxy-3H-isobenzofuran-1-one (1a) and two equivalents of aryl Grignard reagents is described. The title compounds are obtained in medium to high isolated yields. Crude isobenzofuran has also been trapped by maleimide, furnishing pure Diels-Alder adduct almost quantitatively.

Key words

Grignard reactions - Diels-Alder reactions - fused-ring systems - heterocycles - nucleophilic addition

References and Notes

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14

An alternative pathway could be nucleophilic addition of 3a to the carbonyl group of 1a as the first step. This seems unlikely, as the sole isolated compound resulting from reaction of 1a with only one equiv of 3a was phthalide 4a.