Intramolecular Baylis-Hillman and morita reactions using unsaturated thiol ester substrates containing enolizable aldehydes.

[reaction: see text] Previously unknown intramolecular Baylis-Hillman and Morita reactions involving cyclization of an unsaturated thiol ester onto a pendant aldehyde function are reported. These can be used successfully for the preparation of both cyclopentenols and cyclohexenols, but the results are very sensitive to substrate and precise reaction conditions.