Phosphine-boranes based on the 7-phosphanorbornene framework: a regioselective approach to the monoboranes of the dimers of phospholes

The reaction of dimers of phosphole oxides (3a-e) with an excess of dimethy lsulfide borane follows an unexpected route to give phosphine-boranes 5a-e based on the 7-phosphanorbornene framework in a regioselective manner and i n good yields. In small quantities, the diboranes (10a-e), that can be synt hesized in acceptable yields by the reaction of the corresponding diphosphi nes 12a-e with borane, were also formed. (C) 1999 Elsevier Science Ltd. All rights reserved.