DFT study of the mechanism of the phenylselenoetherification reaction of linalool

Abstract

A systematic study of the mechanism of phenylselenoetherification of a naturally occurring alcohol linalool with PhSe+ was performed at the B3LYP/6-311+G(d,p) level of theory, in conjunction with the CPCM solvation model. The syn and anti reaction pathways were examined in the absence and presence of some Lewis bases (quinoline, piperidine, pyridine, and triethylamine) as catalysts. It was found that the reaction occurs via the phenylseleniranium intermediate, which further suffers a nucleophilic attack of the oxygen to two olefinic carbon atoms. This intramolecular cyclization yields 5-ethenyl-5-methyl-2-[2-(phenylseleno)-prop-2-yl]tetrahydrofuran as the major product and 6-ethenyl-2,2,6-trimethyl-3-phenylselenotetrahydropyran as the minor product. Lewis bases facilitate the reaction by strong hydrogen bonds between the alcoholic hydrogen and nitrogen of an additive moiety, and they stabilize the product complexes. Since the formation of the tetrahydrofuran derivative requires higher activation energy, but is thermodynamically more stable than the tetrahydropyran, it was concluded that the phenylselenoetherification reaction of linalool is thermodynamically controlled.