Naokazu Kano

We report conjugated methine compounds generated from N-arylpyridiniums and amines; streptocyanines can be used as a new activation mode for amine catalysis and applied to the conversion of pyridine rings to benzene rings.

Abstract Ligand coupling on sulfur, as an alternative to transition-metal-catalyzed cross-coupling reactions, is a useful method for connecting sp2 carbons. Although pioneered more than 50 years ago, its synthetic utility has been overlooked until recently. This short review summarizes progress in C(sp2)–C(sp2) bond formation using ligand coupling on sulfur and discusses control of selectivity, expansion of the scope, and applications of the reaction. 1 Introduction 2 Cross-Coupling of Heteroaryl Reagents 3 Phenothiazinium-Mediated C(sp2)–C(sp2) Cross-Coupling 4 C(sp2)–C(sp2) Bond Formation Mediated by Sulfuranes Generated from Arynes and Sulfoxides 5 S-Alkenylbenzothiophenium-Mediated Alkenyl-Alkenyl Coupling 6 Conclusion