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

Abstract

. Can. J. Chem. 55,4135 (1977).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. Polymer 2 reacted with the symmetrical diols, 1,s-octanediol and 1, lO-decanediol, to give the monoblocked polymer-bound diols 5 and 6 respectively. Mesylation of 5 and 6 gave the polymer-bound monomesylates 7 and 8 which on coupling with lithioacetylide gave the polymer-bound terminal alkynes 9 and 10 respectively. Acid cleavage of 9 and 10 provide 9-decyn-1-01 and 11-dodecyn-1-01 respectively. A second coupling step was performed by lithiation of 9 and 10 with n-butyllithium or tert-butyllithium followed by treatment with n-butyl bromide or ethyl bromide to give polymer-bound internal alkynes, which on acid hydrolysis gave 9-tetradecyn-1-01 (22), 11-hexadecyn-1-01 (23), and 11-tetradecyn-1-ol(24). If 10 had been lithiated with n-butyllithium and coupled with ethyl bromide, some translithiation occurred to liberate n-butyl bromide which entered into the coupling reaction eventually giving a mixture of 23 and 24. This problem was resolved by the use of tert-butyllithium in the lithiation step. Attempts were made to reduce polymer-bound internal alkynes stereoselectively to cis-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 to cis insect sex attractants using disiamylborane without concurrent overreduction or hydrogenolysis. THOMAS M. FYLES, CLIFFORD C. LEZNOFF et JOHN WEATHERSTON. Can. J. Chem. 55,4135 (1977).On a utilist un copolymere divinylbenzkne-styrkne rCticul.4 a 2% et incorporant des groupes chlorure de trityle (2) pour rCaliser la synthtse de l'attirant sexuel du Lepidoptera en faisant appel a un schtma de couplage d'alcynes impliquant deux Ctapes. I,e polymtre 2 rCagit avec les diols symCtriques octanediol-1,s et dtcanediol-l,l0 pour conduire suivant le cas aux diols monobloquCs 5 et 6 liCs au polymtre. La mksylation de 5 et 6 fournit les monomCsylates 7 et 8 lies au polymere qui, par couplage avec I'acCtylure de lithium, conduisent respectivement aux alcynes terminales 9 et 10 liCs au polymtre. Une scission acide de 9 et 10 conduit respectivement aux dCcyn-9 01-1 et dodCcyn-11 01-1. Une nouvelle Ctape de couplage, effectute par la lithiation I de 9 et 10 avec le n-butyllithium ou le tert-butyllithium, suivie par un traitement avec le bromure de n-butyle ou le bromure d'Cthyle conduit aux alcynes internes liCs au polymtre qui par hydrolyse acide fournissent le tCtradCcyn-9 01-1 (22), I'hexadCcyn-11 01-1 (23) et le tCtradCcyn-11 01-1 (24). Si l'on avait effectuk la lithiation de 10 avec du n-butyllithium et si on I'avait couplC avec du bromure d7Cthyle, il se serait produit un peu de translithiation pour IibCrer du bromur...

Effect of bond‐length alternation on the dipole hyperpolarizability of phenol blue

“…Ellman and co‐workers' linker based on the tetrahydopyranyl (THP) protecting group is analogous to a simple resin‐bound vinyl ether proposed by Wang and is cleaved under the usual acidic conditions, (Table 13, entry 1; PACT H−OR) 72a–72e. Leznoff and co‐workers have made use of the acid‐labile trityl protecting group in the synthesis of various insect pheromones on the solid phase (Table 13, entry 2) 73a,73b,73d,73e…”

Insect Pheromones: A Critical Review of Recent Advances in Their Chemistry, Biology, and Application

“…Solid phase syntheses of alkynols and alkenols have been achieved by LEZNOFF et al (189,193) using polymer-bound symmetrical alkane diols.…”

Syntheses of unconjugated (Z,Z)-diolefinic insect pheromones on insoluble polymer supports

“…A wide variety of syntheses of insect pheromones has been described (Henrick, 1977;Rossi, 1977). In our own laboratories we have synthesized a large number of stereochemically pure monoolefinic insect pheromones (Svirskaya et al, 1979;Fyles et al, 1977;Leznoff et al, 1977) on insoluble polymer supports (Leznoff, 1978;Fr6chet, l98l). One advantage of using the I or 2Tostyrene-divinylbenzene copolymer supports containing trityl chloride groups (Fyles and Leznoff ,197 6; Frdchet et al, I 976) was the selective monoblocking by the polymer of the symmetrical diol starting materials by the "fishhook" principle (Leznoff, 1978).…”

“…One advantage of using the I or 2Tostyrene-divinylbenzene copolymer supports containing trityl chloride groups (Fyles and Leznoff ,197 6; Frdchet et al, I 976) was the selective monoblocking by the polymer of the symmetrical diol starting materials by the "fishhook" principle (Leznoff, 1978). Other advantages include a stereoselective Wittig reaction simulating o'salt-free" conditions (Leznoff et al, 1977\ and a facile borane addition reaction in which borane impurities are removed by simple filtration of the polymer (Fyles et al,1977). Finally, the whole procedure of pheromone synthesis on solid phases has the potential to be automated, as shown for polypeptide (Erickson and Merrifield,1976) and now oligonucleotide synthesis (Alvarado-Urbina et al, l98l).…”