In conclusion, we have described a general route to seven-membered P/N-containing heterocycles via azophosphines. This occurs through initial formation of the corresponding five-membered ring, before P-N bond cleavage yields the analogous sevenmembered ring. The stepwise, rather than concerted, nature of these reactions was confirmed by DFT studies, and asymmetric alkynes could be employed for the regioselective synthesis of new heterocycles. The incorporation of B(C6F5)3 revealed both catalytic activity, and allowed for trapping of a reaction intermediate via a frustrated Lewis pair-type mechanism. We are continuing to explore the reactivity of the five-membered and seven-membered heterocycles with small molecules for future applications.