Synthesis of spiropyrans via Ru(ii)-catalyzed coupling of 3-aryl-2H-benzo[b][1,4]oxazines with benzoquinones

Abstract

An efficient Ru(II)-catalyzed C–H activation-based spiroannulation of benzoxazines with the easily available benzoquinone and N-sulfonyl quinone monoimine has been realized, providing a straightforward strategy to access NH-containing spiropyrans in moderate to good yields with good functional group compatibility. The procedure features atom- and step-economy, mild conditions, and excellent chemoselectivity. Moreover, a catalytically competent five-membered cycloruthenated complex has been isolated.