Junjappa–Ila (JI) Heteroaromatic Annulation: A New General α‐Oxoketene Dithioacetals Mediated Inverse Method for Synthesis of Substituted Benzothiazoles

Abstract

3‐(Methylthio)‐5‐oxo‐2‐(2‐phenyl‐1,3‐thiazol‐4‐yl)‐4,5‐substituted‐pent‐2‐enenitriles 3a–j were obtained in good yields by condensation of (2‐phenyl‐1,3‐thiazol‐4‐yl)‐acetonitrile (1) with various α‐oxoketene dithioacetals 2a–j in the presence of sodium hydride. The intermediates 3a–j underwent smooth cyclization in the presence of PTSA to afford the corresponding benzothiazoles 4a–j in moderate yields.

Keywords:

• Benzothiazole
• JI heteroaromatic annulation
• α‐oxoketene dithioacetal

Acknowledgments

The authors are grateful to the Astra Zeneca Research Foundation, Bangalore, for financial assistance and to BioOrganics, Bangalore, for providing necessary facilities. Our thanks are due to H. Junjappa of BioOrganics and H. Ila of IIT Kanpur, India.