Phosphole is the organic compound with the chemical formula C4H4PH; it is the phosphorus analog of pyrrole.

Unlike the related 5-membered heterocycles pyrrole, thiophene, and furan, the aromaticity of phospholes is diminished, reflecting the reluctance of phosphorus to delocalize its lone pair.

[6] One route to phospholes is via the McCormack reaction, involving the addition of a 1,3-diene to a phosphonous chloride (RPCl2) followed by dehydrohalogenation.

[5] 2,5-Diphenyl phospholes can be functionalised by deprotonation followed by P-acylation then a 1H, 2H, 3H phospholide equilibrium resulting in a 1:3 shift of the acyl group.

[9] Phospholes can also be turned into β-functional phosphabenzenes (phosphinines, or phosphorine) via functionalisation by imidoyl chloride and insertion.