Carbaborane-Substituted 1,2,3-Triphospholanes and 1-Aza-2,5-diphospholane: New Synthetic Approaches

New phosphorus‐containing, five‐membered P,P,P and P,N,P heterocycles were synthesized and fully characterized. The P,P,P heterocycles, 1,2,3‐triphospholanes, can be synthesized by two different facile pathways, whereas the P,N,P compound, a 1‐aza‐2,5‐diphospholane, can only be obtained with silylamine. Carbaboranyl‐based triphospholanes (see figure) are readily available by two synthetic routes. The carbaboranyl backbone renders these phosphaheterocycles water stable and moderately air stable.