Preliminary investigation of the [3+2] cycloaddition reactions of 2-alkylidenephosphiranes

The 2-alkylidenephosphirane complex 1 reacts with norbornene and dimethyl acetylenedicarboxylate at 100 degrees C in toluene to give the corresponding [3+2] cycloadducts. With norbornene, only the P-C distal bond is involved, whereas with acetylenedicarboxylate, both the P-C distal and proximal bonds react.