The Use of Mercury Compounds in the Synthesis of Some Lepidoptera Insect Sex Pheromones with Monoenic Structure

New and practical synthesis of (E)-11-tetradecen-1-yl acetate and (Z)-11-hexadecen-1-yl acetate were developed. The synthesis were based on a C12+C2=C14 and C12+C4=C16 coupling scheme. The routes involve, as the key step, the use of the same mercury derivative of the terminal-alkyne w-functionalised as intermediate.The first coupling reaction was effected by adding 1-tert-butoxy-10-bromodecane to monosodate acetylene, obtained in situ from DMSO and sodium hydride. It was prepared 1-tert-butoxy-dodec-11-yne, which is transformed in di[tert-butoxy-dodec-11-yne]mercury, the common intermediate in the synthesis of the two pheromones. In order to obtain (E)-11-tetradecen-1-yl acetate, the mercury derivative was directly lithiated and then alkylated with 1-bromoethane obtaining 1-tert-butoxy-tetradec-11-yne. After reduction with lithium aluminium hydride of 1-tert-butoxy-tetradec-11-yne and acetylation gave (E)-11-tetradecen-1-yl acetate with 99 % isomeric purity. In order to obtain (Z)-11-hexadecen-1-yl acetate, the mercury derivative was directly lithiated and then alkylated with 1-bromobutane obtaining 1-tert-butoxy-hexadec-11-yne. After acetylation of 1-tert-butoxy-hexadec-11-yne and stereoselective reduction in the presence of NiP-2 catalyst gave (Z)-11-hexadecen-1-yl acetate with 90 % isomeric purity.

STEREODIRECTED SYNTHESIS OF (Е)- AND (Z)-ISOMERS OF 8-CHLOROOCT-7-EN-4-ONE

For citation:Shakhmaev R.N., Sunagatullina A.Sh., Alieva R.M., Zorin V.V. Stereodirected synthesis of (Е)- and (Z)-isomers of 8-chlorooct-7-en-4-one. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 1. P. 40-44. Reaction of ethyl 3-oxohexanoate with equimolar amounts of (E)- or (Z)-1,3-dichloro-propene under phase transfer catalysis conditions in the presence of K2CO3 afforded the corresponding monosubstituted (E)- or (Z)-isomers of ethyl 2-(3- chloroprop-2-en-1-yl)-3-oxohexa-noate and considerable amount of disubstituted derivatives (30-40%). In order to increase yields of monosubstituted derivatives we carried out research to test the known methods of selective monoalkylation of β-dicarbonyl compounds with respect to test substrates. Alkylation of ethyl 3-oxohexanoate in the presence of tetrabutylammonium fluoride and cobalt salts have not led to a significant increase in reaction selectivity, but in the reaction in solid in the absence of solvent the formation of disubstituted products is not practically observed. In the reaction of ethyl 3-oxo-hexanoate with (E)- or (Z)-isomers of 1,3-dichloropropene on the surface of Al2O3 impregnated with t-BuOK monosubstituted products are formed with the yields of 81 and 79%, respectively. Solid phase alkylation proceeds with high stereoselectivity, isomeric purity of target products are greater than 99%. Standard methods of monoalkylated ketoesters decarboxylation under acidic or basic conditions lead to low yields of the corresponding chlorovinyl ketones, best results are obtained at decarboxylation of (E)- or (Z)-isomers of ethyl 2-(3-chloroprop-2-en-1-yl)-3-oxohexa-noate in slightly modified Krapcho conditions. Carrying out the reaction in N-metrhylpirroli-dinone at a temperature of 130-140 °C in the presence of 3 eq. LiCl leads to (E)- and (Z)-isomers of 8-chlorooctyl-7-ene-4-one with 81 and 77% yields, respectively, and an isomeric purity of ~ 99%.

A Practical Synthesis of (Z)- and (E)-8-Dodecene-1-yl Acetate, Components of Lepidoptera Insect Sex Pheromones

New and practical synthesis of (Z)-8-dodecene-1-yl acetate and (E)-8-dodecene-1-yl acetate were developed. The synthesis were based on a C3+C6=C9 and C9+C3=C12 coupling scheme, the starting material being 2-propyn-1-ol and 1,6-hexandiol. The routes involve, as the key step, the use of the same mercury derivative of the terminal-alkyne w-functionalised as intermediate. The first coupling reaction took place between methoxyallene and Grignard reagent of 1-tert-butoxy-6-bromo-hexan obtaining 1-tert-butoxy-non-8-yne, which is transformed in di[1-tert-butoxy-non-8-yne]mercury, the common intermediate in the synthesis of the two pheromones. In order to obtain (Z)-8-dodecene-1-yl acetate and (E)-8-dodecene-1-yl acetate, the mercury derivative was directly lithiated and then alkylated with 1-bromo-propan obtaining 1-tert-butoxy-dodec-8-yne. After acetylation of 1-tert-butoxy-dodec-8-yne and stereoselective reduction in the presence of NiP-2 catalyst gave (Z)-8-dodecene-1-yl acetate with 85 % isomeric purity. After reduction with lithium aluminium hydride of 1-tert-butoxy-dodec-8-yne and acetylation was obtained (E)-8-dodecene-1-yl acetate with 90% isomeric purity.

Impact of fullerene derivative isomeric purity on the performance of inverted planar perovskite solar cells

The effect of utilizing a pure cis-α-dimethoxy carbonyl fulleropyrrolidine C70 (DMEC70) isomer as the electron transporting material (ETM) in inverted perovskite solar cells (PSCs) was evaluated.

A Study on the Lipase-catalysed Acylation of 6,7-Dihydroxy-linalool

We here describe a study of the enzyme-mediated acylation reaction of 6,7-dihydroxy-linalool stereoisomers, which are natural triols occurring in different vegetal species. We found that only few lipases are able to catalyze the acylation of the secondary hydroxy group present in these isomers and only lipase from Candida rugosa and novozyme 435 provide either (3 R,6 R)-6-acetoxy-7-hydroxylinalool or (3 R,6 S)-6-acetoxy-7-hydroxylinalool in moderate and very good isomeric purity, respectively Even for these favorable cases the reaction proceeds very sluggishly. Our finding can give a sensible interpretation to the fact that 6-acyl-7-hydroxy-linalool derivatives do not occur in nature, whereas the corresponding glycosides, whose formation is catalyzed by glycosidase, are very common.