A Convenient Synthesis of 1,2,4‐ and 1,3,4‐Azadiphospholes

A new synthetic route to functionalized neutral and anionic azadiphospholes from easily accessible starting materials is described. Equimolar reaction of Na(OCP) and N‐(2,6‐dimethylphenyl)pivalimidoyl chloride 2 a cleanly affords the imidoxy‐functionalized 1,2,4‐azadiphosphole 3 a . Using Na(OCP) and imidoyl chloride in a 2:1 ratio leads to an anionic four‐membered ring Na 4 a ], which has been structurally characterized. During 16 h at room temperature, Na 4 a ] rearranges to the anionic 1,3,4‐azadiphospholide Na 5 a ] with release of carbon monoxide. Applying the more sterically demanding N‐(2,6‐diisopropylphenyl)pivalimidoyl chloride allows isolation of the 1,3,4‐azadiphospholide Na 5 b ] in good yield (>70 %). Possible mechanisms leading to the new isomeric azadiphospholides have been investigated with the aid of high‐level composite calculations.