Recommanded Product: 16400-32-1. So far, in addition to halogen atoms, other non-metallic atoms can become part of the aromatic heterocycle, and the target ring system is still aromatic. Compound: 1-Bromo-2-pentyne, is researched, Molecular C5H7Br, CAS is 16400-32-1, about Total Syntheses of All Six Chiral Natural Pyrethrins: Accurate Determination of the Physical Properties, Their Insecticidal Activities, and Evaluation of Synthetic Methods.
Chiral total syntheses of all six insecticidal natural pyrethrins (three pyrethrin-I and three pyrethrin-II compounds) contained in the chrysanthemum (pyrethrum) flower were performed. Three common alc. components [(S)-cinerolone, (S)-jasmololone, (S)-pyrethrolone] were synthesized: (i) Straightforward Sonogashira-type cross-couplings using available (S)-4-hydroxy-3-methyl-2-(2-propynyl)cyclopent-2-en-1-ones (the prallethrin alc.) for (S)-cinerolone (overall 52% yield, 98% ee) and (S)-pyrethrolone (overall 54% yield, 98% ee) and (ii) traditional decarboxylation-aldol condensation and lipase-catalyzed optical resolution for (S)-jasmololone (overall 16% yield, 96% ee). Two counter acid segments of [(1R,3R)-chrysanthemic acid (A) and (1R,3R)-second chrysanthemic acid precursor (B)] were prepared: (i) C(1)-epimerization of Et (±)-chrysanthemates and optical resolution using (S)-naphthylethylamine to afford A (96% ee) and (ii) concise derivatization of A to B (96% ee). All six pyrethrin esters (cinerin I/II, jasmolin I/II, pyrethrin I/II) were successfully synthesized utilizing an accessible esterification reagent (TsCl/N-methylimidazole). To investigate the stereostructure-activity relationship, all four chiral stereoisomers of cinerin I were synthesized. Three alternative syntheses of (±)-jasmololone were investigated (methods utilizing Piancattelli-rearrangement, furan-transformation, and 1-nitropropene-transformation). Insecticidal activity assay (KD50 and IC50) against the common mosquito (Culex pipiens pallens) revealed that (i) pyrethrin-I > pyrethrin-II, (ii) pyrethrin I(II) > cinerin I(II) >> jasmolin I(II), (iii) “”natural”” cinerin I >> three “”unnatural”” cinerin I compounds (apparent chiral discrimination).
In addition to the literature in the link below, there is a lot of literature about this compound(1-Bromo-2-pentyne)Recommanded Product: 16400-32-1, illustrating the importance and wide applicability of this compound(16400-32-1).
Reference:
Tetrahydropyran – Wikipedia,
Tetrahydropyran – an overview | ScienceDirect Topics