Synthesis of ubiquinones. Elongation of the heptaprenyl side-chain in ubiquinone-7

Abstract

Regio- and stereo-chemically selective transformation of the terminal trans-methyl group of the heptaprenyl side-chain in ubiquinone-7 (1a; n= 6) and its O-benzylated quinol (1b) into the trans-chloromethyl group and the coupling of the resulting compound (10b) with prenyl, geranyl, and farnesyl p-tolyl sulphones (14a, b, c), with subsequent reductive elimination of p-tolylsulphonyl and benzyl groups and oxidation of the corresponding quinols, have resulted in a novel synthesis of ubiquinone-8, -9, and -10 (1a; n= 7,8, and 9). ¹H and ¹³C n.m.r. spectra of ubiquinone-7 and its derivatives, and of several sulphones as reference compounds, are discussed.