An (S)-(+)-Lactic Acid Route to (2S,6R,8S)-2,8-Dimethyl-1,7-dioxaspiroundecane and (2S,6R,8S)-2-Ethyl-8-methyl-1,7-dioxaspiroundecane and Demonstration of their Presence in the Rectal Glandular Secretion of Bactrocera nigrotibialis (Perkin)

Article abstract of DOI:10.1039/P19900002501

The chiral iodide resulting from reduction and iodination of the tetrahydropyran-2-yl ether of ethyl (S)-(+)-lactate has been engaged in a free-radical addition to acrylonitrile.The resulting protected hydroxy nitrile, on reaction with pent-4-enylmagnesium bromide afforded (S)-2-tetrahydropyran-2-yloxyundec-10-en-6-one.Oxymercuration of this hydroxy enone, under reversible conditions, employing aqueous acid-tetrahydrofuran, effected simultaneous deprotection and cyclisation, and in situ biphasic demercuration with sodium borohydride provided essentially stereochemically pure (2S,6R,8S)-2,8-dimethyl-1,7-dioxaspiro<5.5>undecane .Epoxidation of the protected hydroxy enone, followed by dimethylcuprate ring-opening and cyclisation, provided a mixture of the (E,E) and the two possible (E,Z)-diastereomers of 2-ethyl-8-methyl-1,7-dioxaspiro<5.5>undecane with the former being the (2S,6R,8S) stereoisomer.Separation of the (E,E) from the two (E,Z) isomers was achieved by preparative gas chromatography.GC analysis of these samples and of the rectal glandular secretion of male Bactrocera nigrobialis, using a cyclodextrin-based phase, demonstrated that (2S,6R,8S)-stereoisomers of the 2,8-dimethyl-and 2-ethyl-8-methyl-1,7-dioxaspiro<5.5>undecanes were the natural products, with no detectable level of the antipodes.

Full text of DOI:10.1039/P19900002501

View Article Online / Journal Homepage / Table of Contents for this issue

View Article Online

View Article Online

View Article Online

View Article Online

View Article Online