Roy G. Miller

Rhodium catalyzed hydroacylation of ethylene with 4-pentenals. reactions of 4-hexenal-1-d

Abstract 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 possessing >50% do molecules while the isotopic composition of recovered unexpended 4-hexenal remained >96% d1. 6-Octen-3-one products with isotopic compositions of >66% do 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.

A stereospecific rhodium catalyzed hydroacylation. Cyclization of trans-4-hexenal-1-d

Treatment of trans-4-hexenal-1-d with RhCl(PPh3)3 (I) in C6 H6 afforded 2-methylcyclopentanone-3-d and -2-d (II-3-d, and II-2-d) in 91 ratio when the reaction was carried to a low conversion. The deuterium in the II-3-d product was found to be cis to the C(2) methyl group by analysis of the 270 MHz 1H and 41.4 MHz 2H NMR spectra. This analysis was assisted by the synthesis of II-cis-2,3-d2 by treatment of 2-methylcyclopent-2-en-1-one with D2 and I. The 270 MHz 1H and 41.4 MHz 2H spectra of II-cis-2,3-d2 and of II-2,5,5-d3 were instrumental in the assignments of proton resonances in spectra of II-3-d. The results demonstrated that the cyclization of 4-hexenal-1-d occurred by a syn addition of the CD bond to the olefinic bond to generate II-3-d. The results were interpreted in terms of a mechanism involving intervention of an acylrhodium(III) hydride complex and organorhodium(III) intermediates derived therefrom.

A carbon-nickel addition to benzyne

The thermal decomposition of benzenediazonium-2-car☐ylate in the presence oftrans-(phenylethynyl)(trichlorovinyl)bis(triethylphosphine)nickel(II), (I), in dichloromethane affords [2-(phenylethynyl)phenyl] (trichlorovinyl)bis(triethylphosphine)nickel(II) < (III). Also present in the product mixtures way 2-(phenylethynyl)(trichlorovinyl)benzene, (IV), which was shown to be formed from (III) under the reaction conditions employed. Evidence is presented which indicates that (III) is derived from a carbon-nickel addition to benzyne.

Thermal decomposition of trans-chloro(2-allylphenyl)bis(triethylphospine)nickel(II)☆

Abstract Thermolysis of trans -chloro(2-allylphenyl)bis(triethylphosphine)nickel(II), I, in tetrachloroethylene has afforded indene as the major hydrocarbon product along with lesser amounts of allylbenzene and trans -β-methylstyrene. Organonickel products were trans -chloro(trichlorovinyl)bis(triethylphosphine)nickel(II), II, chloro[2-( trans -propenyl)phenyl]bis(triethylphosphine)nickel(II), III, and trans -dichlorobis(triethylphosphine)nickel(II). Compound III was the major product from thermolysis of I in benzene. Chloro[2-( cis -propenyl)phenyl]bis(triethylphosphine)nickel(II), IV, and III could be synthesized independently by treatment of chloro-2-( cis -propenyl)benzene and chloro-2-( trans -propenyl)benzene, respectively, with nickel acetylacetonate and triethylaluminium in the presence of triethylphosphine. Thermolysis of I in benzene containing allylbenzene led to the formation of trans -β-methylstyrene. The thermolysis of I in benzene in the presence of cis -1,4-hexadiene caused the skeletal rearrangement of the diene to trans -2-methyl-1,3-pentadiene. A catalyst derived from ethylenebis(triphenylphosphine)nickel(0) and hydrogen chloride isomerized allylbenzene to trans -β-methylstyrene.