Unexpected Behaviour of Monospirothiacalix[4]arene under Acidic Conditions.

Abstract

Treatment of the monospirodienone derivative of thiacalix[4]arene with various acidic agents (HCl and HBr) results in rearrangement of the thiacalixarene skeleton leading to the formation of a phenoxanthiin derivative in high yields (up to 80%). The structure of the unexpected product is confirmed using1H and 13C NMR spectroscopy, and X-ray crystallography.

Keywords

• spirodienone route
• derivatives
• functionalization