RHODIUM CATALYZED HYDROACYLATION OF ETHYLENE WITH 4-PENTENALS. REACTIONS OF 4-HEXENAL-1-d

Article abstract of DOI:10.1016/S0022-328X(00)94430-9

A catalyst derived from 2,4-pentanedionatobis(ethylene)rhodium(I), I, promoted the addition of 4-pentenal to ethylene.The reaction was accompanied by the formation of double bond migration products derived from the 4-pentenal reactant and from the 6-hepten-3-one primary product.Compound I accomplished the addition of 4-hexenal to ethylene to afford high yields of 6-octen-3-one.The fate of the aldehyde hydrogen in this transformation has been determined in experiments employing 4-hexenal-1-d as reactant.Treatment of 4-hexenal-1-d with I in CHCl3 and CDCl3 afforded 6-octen-3-one possesing > 50percent d₀ molecules while the isotopic composition of recovered unexpended 4-hexenal remained > 96percent d₁. 6-Octen-3-one products with isotopic compositions of > 66percent d₀ were afforded when ethylene was introduced to reaction mixtures.The location of deuterium in 6-octen-3-one, derived from treatment of 4-hexenal-1-d with I in the absence of added C2H4, was determined to be distributed at C-1 and C-2 and at the C=C bond by analysis of the 1H and 2H NMR spectra.Unexpended ethylene was recovered and was found to contain a substantial amount of deuterium.Mechanistic implications of these results are discussed.