N. Ya. Grigor'eva

Stereoselective synthesis of a dolichol-like octaprenol (S)-WT3C3SOH

In accordance with the previously developed block method of constructing polyprenol molecules, a new stereospecific synthesis was carried out of their natural representative WT3C2OH, which was then converted in nine steps into the above chiral octaprenol. At the same time the synthesis of the racemate of the latter has been improved.

HIGHLY STEREOSELECTIVE SYNTHESIS OF A SEX PHEROMONE OF THE DRY BEAN BEETLECALLOSOBRUCHUS ANALIS

Total synthesis of 3-methylhept-2(Z)-enoic acid, a sex pheromone of the dry bean beetleCallosobruchus analis, has been performed using a previously developed highly stereoselective method of the construction of disubstituted (Z)-methylolefins based on the higher thermodynamic stability of (E)-isomers of α,β-disubstituted acroleins.

An alternative synthesis of a sex pheromone of the dry bean beetleCallosobruchus analis

A formal total synthesis of 3-methylhept-2(Z)-enoic acid, a sex pheromone of the dry bean beetleCallosobruchus analis, was performed on the basis of a highly stereoselective version of the Peterson olefination of ketones developed previously by the authors.

Synthesis of Z,Z-Trishomofarnesal tert-butylimine

A highly stereoselective method was developed for the preparation of Z,Z-trishomofarnesal tert-butylimine, a key block synthone required for the construction of polyprenols with a nonnatural configuration of the “head” end of the chain, using as a basis the controlled condensation of aldehydes with aldimines. It was shown that introduction into the condensation of aldehydes containing an acetal grouping at the ω-position results in the formation of considerable amounts of aldols. The use of α-trimethylsilyl derivatives of aldimines makes it possible to dispense with this process and to direct the reaction toward the desired Eacroleins.

NMR investigation of some α,ω-disubstituted farnesanes

ConclusionsNew, independent evidence for the twisted conformation of linear isoprenoid molecules has been obtained from a study of the13C NMR spectra of the ethyl ester isomers of 11-bromo-10-hydroxy, 10, 11-epoxy, and 10, 11-dihydroxy-3, 7, 11-trimethyldodeca-2E/Z, 6E/Z-dienecarboxylic acids when compared with the corresponding ethyl esters of 3, 7, 11-trimethyldodeca-2E/Z,6E/ Z,10-trienecarboxylic acid (farnesyl ester). Further information came from an NOE study of the latter and the ethyl esters of 10-formyl-3,7-dimethyldeca-2E,6E/Z-dienecarboxylic acid.

Reaction of isoprenoid olefins with SeO2 in aprotic solvents

Conclusion1.Previously unknown Se-organic compounds, the structure of which confirm the formation of allylseleninic acids as the primary intermediates of this reaction, were isolated in the reaction of geraniol benzyl ether and linalool and citronellol acetates with SeO2 in lowpolarity aprotic media; the products were also characterized.2.An explanation of the results was proposed; this explanation includes conversion of the allylselenine intermediates to allylselenene intermediates, which then react intermolecularly or intermolecularly with the C=C bond to give cyclic or linear selenides.

Directed aldol condensation as a stereoselective method for the synthesis of Z-trisubstituted olefins

Conclusions1.The directed aldol condensation with higher aldehydes and aldimines, including functionally substituted compounds, can serve as a highly stereoselective preparative method for the production of the E-disubstituted acroleins, which are readily transformed into the corresponding Z-trisubstituted olefins.2.The potentialities of the method are illustrated by the synthesis of the heptaprenols ωtttcccOH and ωtttcctOH.

Decarbonylation of aliphatic α,β-unsaturated aldehydes using the Wilkinson complex

ConclusionsThe decarbonylation of α,β-unsaturated α,β-disubstituted aliphatic aldehydes in the presence of the Rh(PPh3)3 complex proceeds only at temperatures above 100° and is not a stereospecific reaction.

Determination of the Z, E configuration of functionally trisubstituted olefins by13C NMR

Conclusions1.The Z, E configuration of functional trisubstituted olefins was established by means of13C NMR.2.CX, the constant of spin-spin coupling with the allyl protons of the R substituent, is characteristic; it is 5.0 and 3.5 Hz for E and Z isomers, respectively.3.The chemical shift values for the olefinic carbon Cβ in α,β-unsaturated aldehydes permit the assumption that conjugation of the olefin bond is more effective in E isomers than in Z isomers.

Building blocks for acyclic polyisoprenoid synthesis based on isomeric farnesenate esters

Conclusions1.Four oxidative methods of converting E,E-, Z,E-, E,Z- and Z,Z-farnesenate esters into the corresponding isomeric ethyl 10-oxo-3,7-dimethyl-2,6-decadienoate esters have been investigated with the object of synthesizing a set of stereoisomeric blocks for building up acyclic isoprenoids. The best method is preparative ozonolysis, giving yields of 50% based on the farnesenate ester reacted.2.Differences are observed in the reactivity of the isomeric farnesenate esters containing Z6 and E6 double bonds.