The synthesis of stable 1,3,4-triphenylphospholes

The first syntheses of 1,3,4-triphenylphosphole, 2-bromo-1,3,4-phenylphosph ole and 2,5-dibromo-1,3,4-triphenylphosphole are described. These phosphole s, unlike most of the known derivatives, are difficult to oxidise and they and their corresponding oxides show little tendency to dimerise. The NBS me diated bromination of 1,3,4-triphenyl-2,5-dihydrophosphole oxide led to the desired precursors of the corresponding phospholes and in one case unexpec tedly yielded a phosphole oxide directly. Some reactions including the form ation of organolithium reagents and their derivatisation are reported. McMu rry reactions of derived formylphospholes to give coupled products are desc ribed and some copper mediated reactions are also discussed.