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The use of polymer supports in organic synthesis. XII. The total stereoselective synthesis ofcisinsect sex attractants on solid phases

 

作者: Thomas M. Fyles,   Clifford C. Leznoff,   John Weatherston,  

 

期刊: Canadian Journal of Chemistry  (NRC Available online 1977)
卷期: Volume 55, issue 23  

页码: 4135-4143

 

ISSN:0008-4042

 

年代: 1977

 

DOI:10.1139/v77-586

 

出版商: NRC Research Press

 

数据来源: NRC

 

摘要:

A 2% crosslinked divinylbenzene-styrene copolymer, incorporating trityl chloride groups (2) was used in the synthesis of insect sex attractants of Lepidoptera by a two-step alkyne coupling route. Polymer2reacted with the symmetrical diols, 1,8-octanediol and1,10-decanediol, to give the monoblocked polymer-bound diols5and6respectively. Mesylation of5and6gave the polymer-bound monomesylates7and8which on coupling with lithioacetylide gave the polymer-bound terminal alkynes9and10respectively. Acid cleavage of9and10provide 9-decyn-1-ol and 11-dodecyn-1-ol respectively. A second coupling step was performed by lithiation of9and10withn-butyllithium ortert-butyllithium followed by treatment withn-butyl bromide or ethyl bromide to give polymer-bound internal alkynes, which on acid hydrolysis gave 9-tetradecyn-1-ol (22), 11-hexadecyn-1-ol (23), and 11-tetradecyn-1-ol (24). If10had been lithiated withn-butyllithium and coupled with ethyl bromide, some translithiation occurred to liberaten-butyl bromide which entered into the coupling reaction eventually giving a mixture of23and24. This problem was resolved by the use oftert-butyllithium in the lithiation step. Attempts were made to reduce polymer-bound internal alkynes stereoselectively tocis-alkenes with 9-borabicyclononane, diisobutylaluminum hydride, and catechol borane but all these reagents proved inadequate due to incomplete reduction, overreduction, hydrogenolysis of the alkyne from the polymer, and non-selectivity. Polymer-bound internal alkynes were quantitatively reduced exclusively tocisinsect sex attractants using disiamylborane without concurrent overreduction or hydrogenolysis.

 

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