TRANSITION-METAL SUBSTITUTED ACYL PHOSPHANES AND PHOSPHAALKENES .28. REACTIVITY OF METALLOPHOSPHAALKENES (ETA(5)-C(5)ME(5))(CO)(2)FEP=CR(2)(1) (R(1)=SIME(3), NME(2)) TOWARD METHYL AND ETHYL PROPIOLATE

The metallophosphaalkene (eta(5)-C(5)Me(5))(CO)(2)FeP=C (SiMe(3))(2) ( 1) undergoes reaction with 2 equiv of alkyl propiolates HC=CCO(2)R(2) (R(2)=Me, Et) to afford the novel bicyclic P-metalloylides ))=C(CO(2)R (2))OP[=C(SiMe(3))(2)]Fe(CO)(2)[R(2)=Me (8c), Et (8d)]. In contrast to this, metallophosphaalkene (eta(5)-C(5)Me(5))(CO)(2)FeP=C(NMe(2))(2) (2) smoothly adds 3 equiv of the propiolates with formation of the spi robicyclic compounds (eta(5)-C(5)Me(5)) (2))C(NMe(2))(2)C(CO(2)R(2))=C H]CH=C(CO(2)R(2))C=O [R(2)=Me (10c), Et (10d)]. Treatment of equivalen t amounts of methyl propiolate and 2 gave a mixture of P-metallo-1-pho sphabutadiene (5)-C(5)Me(5))(CO)(2)FeP=CHC(CO(2)Me)=C(NMe(2))(2) (6c) and metalloheterocycle -C(5)Me(5))(CO)FeP[=C(NMe(2))(2)]CH=CH(CO(2)Me) C=O (5c). The molecular structure of 8c was determined by single-cryst al X-ray diffraction.