Specific and chemoselective multi-alpha-arylation reaction of benzoylformic acid with or without decarbonylation in P(2)O(5)-MsOH and related acidic media

In P(2)O(5)-MsOH, or related acidic media, benzoylformic acid (1) undergoes three types of di- or mono-alpha-arylation reactions with or without decarbonylation ((1) decarbonylative alpha, alpha-diarylation, yielding triarylmethanols 6, (2) decarbonylative alpha-monoarylation, giving benzophenone derivatives 7, and (3) alpha,alpha-diarylation without decarbonylation, affording diarylated carboxylic acids 5) and one simple decarbonylation, without arylation, to form benzoic acid (8), instead of the conventional Friedel-Crafts acylation type reaction. The product ratios are governed by the capability of the acidic medium to form mixed anhydrides with carboxylic acids and the ability of the arenes to accept electrophiles.