Photolysis of cis-3, 5-dimethyl-l, l-dioxo-2-phenyl-4-thiazolidinone (through a Vycor filter, in t- BuOH/CH&N) gives cis-1, 3-dimethyl-4-phenyl-2-azetidinone in 43% yield and the corresponding trans P-lactam in 11% yield. Photolysis of tra~-3, 5-dimethyl-1, l-dioxo-2- phenyl-4-thiazolidinone gives lower yields of 0-lactam, with the trans stereoisomer predominating. Thermal reaction of the l, l-dioxo-2-phenyl-4-thiazolidinones gives only the ...
