Unexpected Thermal Extrusion of CO₂ from 3-Benzylthiazolidin-2-one 1,1-Dioxides to give 2-Phenylthiazolines and Thiazoles

Flash vacuum pyrolysis of a series of chiral 3-benzylthiazolidin-2-one 1,1-dioxides 5, readily prepared from amino acids, results mainly in loss of SO2 to give an alkene and benzyl isocyanate, but a significant minor pathway involves unexpected loss of CO2 and water to give 2-phenylthiazolines 13 and derived thiazoles.