New Variation of the Aromatic ortho-Claisen Rearrangement: Synthesis of Fused Thiophenes and Pyrroles

The development of a new variation of the aromatic ortho-Claisen rearrangement of aryl propargyl sulfoxides and aryl-propargylamine oxides involving tandem [2,3]- and [3,3]-sigmatropic rearrangements followed by ketolization/S(N)2' displacement to give fused thiophenes and pyrroles, respectively, is described. 1 Introduction 2 The New Variant 3 Mechanism 4 Applications 4.1 Synthesis of Condensed Thiophenes 4.2 Synthesis of Bioactive Heterocycle-Annulated Thiophenes 4.3 Unusual Dehydrogenative Elimination 4.4 Aliphatic Counterpart of the Variant 5 Amine Oxide Counterpart of the Variant 6 Conclusion