O. A. Pinsker

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.

Synthesis of Dolichyl Phosphates with a Fluorescent Label in the gamma-Isoprene Unit of the Chain

Stereoselective synthesis of the dolichyl phosphate derivatives WT3C2S-OP and WT2C6,7S-OP* containing the 1-naphtylamino group in the gamma-isoprene unit of the chain was performed. The synthetic scheme includes directed aldol condensation to construct (E)-alfa,beta-disubstituted acroleins, their reductive amination with 1-aminonaphthalene, and phosphorylation of the resulting amino alcohols.

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.

Z-Stereoselective Peterson olefination of ketones

A highly-stereoselective method (90 % of theZ-isomer) was developed for the Peterson olefination of ketones with nerylacetone (1) as an example. The method is based on the introduction of a PhS group, which is removed after completion of the reaction, at the ketone C(3) atom.

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.

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.

Gas-phase fragmentation studies of cyclic oligo-β-(1→6)-D-glucosamines by electrospray ionization mass spectrometry using a hybrid high-resolution mass spectrometer

Positive and negative ion high-resolution electrospray ionization mass spectra (MS and MS2) of cyclooligo-β-(1→6)-D-glucosamines and cyclooligo-β-(1→6)-N-acetyl-D-glucosamines were acquired and interpret. It was shown that the cleavages of glycosidic bonds are the main processes in the decay of protonated and metallated molecules. In addition, elimination of the water molecules (and ammonia for cyclooligo-β-(1→6)-D-glucosamines) was observed along with other processes including the unknown skeletal rearrangement. A primary fragmentation of the negatively charged ions (deprotonated molecules) differed from that of the positively charged ones.

Stereospecific synthesis of octaprenols WT3C4OH and WT3C3TOH

A total synthesis of the above prenols has been carried out.