A Novel Approach to 1,2,4-Thiadiphospholes and Functionalized 1,2-Thiaphospholes

Abstract

Phosphaalkynes 1 react regiospecifically in the presence of the thiotantalum(V) compound 2 to afford the 1,2,4-thiadiphospholes 3. These compounds can function both as η1 and as η5 ligands in complexes with group-6 metals. [4+2] Cycloaddition reactions only occur with phosphaalkynes or highly reactive acetylenes as reaction partners. These reactions afford on the one hand the functionalized 1,2-thiaphospholes 17 and, on the other hand, the deltacyclenes 23 and 11; the latter undergo noteworthy subsequent reactions. In the course of syntheses of the 1,2-thiaphospholes 17, traces of the tetracyclic cage compounds 18 and 19 can also be isolated.