Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Contributions to the Chemistry of Boron, 219. - (Di-tert-butylphosphanylimino)(2,2,6,6,-tetrametylpiperidino)borane: a BNP 1,3-„Dipole”In contrast to amino-imino-boranes R2N-BN-R', which are susceptible to [2 + 2] cycloadditions, the amino(phosphanyl-imino)borane 2 [R = P(tBu)2] performs [3 + 2] cycloadditions with heteroallenes X≡C≡Y or nitriles to yield the novel five-membered heterocycles 3a-g, 6, 7, and 8. The reactions of 2 are dominated by the phosphorus atom as the nucleophile attacking the carbon atom in X≡C≡Y and R-CN, respectively. The driving force for the formation of the new heterocycles is obviously provided by the formation of an iminophosphorane structure and a three-coordinated environment at the boron atom. The X-ray-structures of 3a, 3c, 3e, and 3g demonstrate planer heterocyclic rings.
Type of Medium: