One-pot synthesis of sulfonyl benzotropones

This paper describes SeO₂-mediated one-pot tandem cyclocondensation of 1,3-bis-sulfonylacetones and <i>o</i>-dimethylarenes <i>via</i> (4 + 3) annulation to construct diverse bis-sulfonyl benzotropones. Under mild conditions, the effective reaction forms two carbon-carbon double (CC) bonds in a single-step process in the formation of a seven-membered ring system. A plausible mechanism is proposed and discussed herein.