Crystalline BP‐Doped Phenanthryne via Photolysis of The Elusive Boraphosphaketene
Wenlong Yang, Kelsie E. Krantz, Diane A. Dickie, Andrew Molino, David J. D. Wilson, Robert J. Gilliard
Abstract
Abstract The synthesis and reactivity study of the first isolable boraphosphaketene, cyclic(alkyl)(amino) carbene (CAAC)‐borafluorene‐P=C=O ( 2 ), is described. Photolysis of compound 2 results in the formation of CAAC‐stabilized BP‐doped phenanthryne ( 3 ) through tandem decarbonylation, monoatomic phosphide insertion, and ring‐expansion. Notably, while BN‐doped phenanthryne was previously discussed as a reactive intermediate which could not be isolated, the heavier BP‐doped analogue exhibits remarkable solution and solid‐state stability. The reactivity of 2 with stable carbenes was also explored. Addition of CAAC to 2 led to migration of the original CAAC ligand from boron to phosphorus and coordination of the added CAAC to carbon, affording compound 4 . Reaction of 1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene (NHC) with 2 resulted in N−C bond activation to give the unusual spiro‐heterocyclic compound ( 5 ).