SYNTHESIS OF 1-PHOSPHASPIRO[2.N]ALKANES BY ADDITION OF TERMINAL PHOSPHINIDENE COMPLEXES TO EXOCYCLIC OLEFINS

The phosphinidene complexes PhPW(CO)5 (1a) and MePW(CO)5 (1b) have bee n added to exocyclic olefins to yield 1-phosphaspiro[2.n]alkanes (n = 2-5). The molecular structures of the parent phosphirane 10a and the p arent phosphaspiro[2.2]pentane 6a that result from addition of PhPW(CO )5 to ethylene and methylenecyclopropane, respectively, have been dete rmined by single-crystal X-ray analyses. The reactivity order for addi tion of both phosphinidene complexes to exocyclic olefins was determin ed as methylenecyclopentane (4) > methylenecyclobutane (3) > methylene cyclohexane (5) > methylenecyclopropane (2). PhPW(CO)5 is more selecti ve and less reactive in its additions than MePW(CO)5. The relative rat es for phosphinidene addition correlate with both C-13 NMR chemical sh ifts of the spiro-carbon and the 1J(CH) coupling constants of the CH2 group of the 1-phosphaspiro[2.n]alkanes products,