A new approach to β-functional phospholes. Application to the synthesis of a β-CH2-CH2-bridged diphosphole disulphide

Article abstract of DOI:10.1016/S0022-328X(00)00834-2

Protection of both the dienic system and the lone pair of phosphorus of 1-phenyl-3,4-dimethylphosphole by complexation with iron carbonyl groups allow the regiospecific deprotonation of one β-methyl substituent by lithium diisopropylamide (LDA). The resulting anion exhibits versatile reactivity towards various electrophiles and can even undergo oxidative coupling with CuCl₂, thus providing an entry into the unprecedented β-β′-bridged biphosphole system. Finally, the protecting iron carbonyl moieties can be cleanly removed in a two-step procedure involving reaction with sulphur and cerium ammonium nitrate (CAN).