Cycloadditions of 3,4-dimethyl-1-thio-1-phenyl phosphole

Phosphole sulfide 1 undergoes cycloaddition to give a new 15-phosphasteroid. The ¹³C-NMR and ²J_PC-coupling constants of several compounds prepared similarly are discussed, permitting structure assignment to one of the 7-phosphabicyclo[2.2.1]heptane adduct 5. Thiophosgene reacts with the PS moiety of 1, giving 12 after hydrolysis, through a PS to PO transformation coupled in case of 1 with a proton migration.