The demand for the efficient assembly of structurally complex molecules from simple starting materials continues to grow alongside advances in organic synthesis. Here, we utilize the ring strain of phosphiranes to construct an 8-thia-2-aza-1-phosphabicyclo3.2.1oct-3-ene skeleton via a tandem reaction of phosphiranide, sulfur, and alkynyl imines. The proposed mechanism involves intramolecular attack by in situ generated allenamine anion on the phosphirane, leading to a C-P bond cleavage and formation of a strained cyclic allene intermediate, which furnishes the bicyclic products.
Xu et al. (Mon,) studied this question.