Hyungeui Lee

Diastereocontrolled synthesis of cis-olefins by selective C–C bond formation between alkyl and alkynyl groups coordinated to “Ir(CHCHPPh3)(CO)(PPh3)2”

cis,cis-1,4-Dipropenylbenzene (cis,cis-p-C6H4(CHCHCH3)2, cis-DPB) and cis,cis,cis-1,3,5-tripropenylbenzene (cis,cis,cis-m,m-C6H3(CHCHCH3)3, cis-TPB) are obtained in high yields by reactions of di- and tri-nuclear alkyl–alkenyl–alkynyl iridium(III) compounds, [p-C6H4(CC–Ir(CH3)(CHCHPPh3)(CO)(PPh3)2)2]2+1 and [m,m-C6H3(CC–Ir(CH3)(CHCHPPh3)(CO)(PPh3)2)3]3+3 with HCl. The reaction of the mono-nuclear alkyl–alkenyl–alkynyl iridium(III) complex, [Ir(CH3)(CHCHPPh3)(CC-p-C6H4CH3)(CO)(PPh3)2]+7a with DCl selectively gives cis-CD3CDCD(p-C6H4CH3) 8a-d5 while two isomers, cis-C6H5CD2CDCD(p-C6H4CH3) 8b-d4 and cis-C6H5CDCDCD2(p-C6H4CH3) 8b′-d4 are obtained from the reaction of [Ir(CH2Ph)(CHCHPPh3)(CC-p-C6H4CH3)(CO)(PPh3)2]+7b with DCl. Plausible reaction pathways containing the initial attack of H+ on the β-carbon of the alkynyl ligands to produce cis-alkenyl complexes that give η2-allene complexes are suggested for the selective and diastereocontrolled C–C bond forming reactions between alkyl and alkynyl groups to give cis-olefins, 8, cis-DPB, and cis-TPB.