Rongqiang Tian

Isomerization of Secondary Phosphirane into Terminal Phosphinidene Complexes: An Analogy between Monovalent Phosphorus and Transition Metals

Secondary phosphirane complexes isomerize above 100 °C to give the corresponding terminal phosphinidene complexes, which can be trapped by alkenes and alkynes. This reaction is a rare instance of the isomerization of a P(III) derivative into a P(I) derivative. It appears to mimic the reductive elimination of alkanes from transition-alkylmetal hydrides.

Reaction of Phospholes with Aldimines: A One-Step Synthesis of Chelating, Alpha-C2-Bridged Biphospholes.

Phospholes react with aldimines at 170 °C in the presence of mild Lewis acids to give C2-bridged biphospholes in good yields. The mechanism includes a series of [1,5] shifts of the P-substituents around the phosphole ring, a P-H + aldimine condensation, and the formation of a transient three-membered ring that dimerizes.

Generation and Trapping of a 1-Phosphafulvene: An Illustration of the P═C/C═C Analogy

1-Phosphafulvenes can be easily generated by dissociation of dimers resulting from the reaction of phospholes with aldimines. As electron-rich partners, they act as 4π phosphadienic systems toward alkenes and alkynes in [4 + 2] cycloaddition reactions. As electron-poor partners, they act either as 2π systems toward conjugated dienes in [2 + 4] cycloaddition reactions via their P═C double bond or as 6π systems toward phosphadienes in [6 + 4] cycloaddition reactions.

The chemistry of 1-acylphosphirane complexes: A phosphorus analogue of the Cloke-Wilson rearrangement

The stabilization of a phosphirane ring by complexation to tungsten pentacarbonyl allows the emergence of the Cloke-Wilson rearrangement in 1-acylphosphirane complexes around 130 °C. Contrary to the cyclopropane case, this transformation of the 1-acylphosphirane to the 1,3-oxaphosphol-3-ene complexes is reversible. It is favored by a 2-phenyl, and even a 2-vinyl substitution. The 1,3-oxaphosphol-3-ene complexes are trapped by conjugated dienes.