RHODIUM CARBONYL-CATALYZED CARBONYLATION OF UNSATURATED-COMPOUNDS .5. CROSS-HYDROCARBONYLATION OF 1-ALKYNE AND ETHYLENE BY RHODIUM CARBONYL CATALYST MODIFIED WITH PHOSPHINES

In the presence of Rh4(CO)12 catalyst modified with triphenylphosphine the cross-hydrocarbonylation of 1-alkyne (RC2H; R = Me, Et, (n)Pr, (n)Bu, and (t)Bu) and ethylene using 2-propanol as the hydrogen donor gives 3-alkyl-5-ethyl-2(5H)-furanone (4, 44-69%), along with a small amount of 4-alkyl-5-ethyl-2(5H)-furanone (5, 1-8%). When acetylene itself is used, gamma-caprolactone (6a), which is the hydrogenation product of the expected 5-ethyl-2(5H)-furanone (4a), is obtained. The yield of 6a depends on the nature of the phosphine employed and decreases in the following order: PR3 = P(C6H4F-p)3 > PPh3 > P(C6H4Me-p)3 > P(C6H4OMe-p)3 > PPh2Et > PPhEt2 > PEt3.