Oxaphosphiranes: isolable phosphorus-containing epoxide rings.

Combining different heteroatoms in an epoxide-type ring having Lewis basic and acidic characteristics is challenging as it creates an increasing number of polar bonds and high ring strain energy. The first examples of isolable oxaphosphiranes, , epoxide rings with a phosphorus atom, have been synthesized using a facile and effective protocol starting from [pentacarbonyl{dichloro(trityl)phosphane}molybdenum(0)] (trityl = CPh), -butyllithium and commercially available fluorinated benzaldehydes. Reactions with various acids and bases will be described. Theoretical results unveil a singlet carbene-like FMO situation at phosphorus in oxaphosphirane, which is used to explain reaction mechanisms.