2,5-[C 4 +C 2 ] Ringtransformation of Pyrylium Salts with α-Sulfinylacetaldehydes.

A rapid synthesis of chiral sulfoxide-functionalized meta -terphenyl derivatives by a 2,5-[C 4 +C 2 ] ring transformation reaction of pyrylium salts with in situ generated enantiomerically pure α-sulfinylacetaldehydes is described in this paper. This synthetic method demonstrates, for the first time, the use of α-sulfinylacetaldehydes in a reaction sequence initiated by the nucleophilic attack of pyrylium salts by α-sulfinylcarbanions to generate chiral aromatic systems. The method presented shows a broad applicability starting with various methyl sulfoxides and a number of functionalized pyrylium salts, furnishing meta -terphenyls with complex substitution patterns from readily accessible starting compounds.