G. B. Elyakov

Total synthesis of compounds related to triterpenoids

ConclusionsIt was shown that it is theoretically possible to synthesize polycyclic structures, related to triterpenoids of the dammarane series, via diene condensation using 2-acetyl-4-methyl-4-cyclopentene-1,3-dione as the dienophile.

Substituent effects in cyclohexenes

SummaryThe effects of the C1-CH3 group in the13C spectra of trans-4,5-dimethylcyclohex-4-ene-1,2-dicarboxylic and syn-txans-Δ4-octalin-1,2-dicarboxylic acid and their diesters show the existence in solution of a considerable proportion of the trans-a,a forms of these compounds.

Substituent effects in the cyclohexenes 1.13C AND1H NMR spectroscopy of cis-4,5-dimethyl-4-cyclohexene and syn-cis-Δ4-octalin-1,2-dicarboxylic acids and their derivatives

Conclusions1.CH3 group effects have been determined in the13C spectra of cis-1,4,5-trimethyl4-cyclohexene-, syn-cis-1-methyl-, and syn-cis-2-methyl-Δ4-octalin-1,2-dicarboxylic acids and their derivatives.2.In the syn-cis-Δ4-octalin-1,2-dicarboxylic acids, and their esters, and in theγ-oxy acids of this same series, the cyclohexene ring is in predominantly in half-chair conformation with the substituent at the C1 atom in the axial position, and the substituent at the C2 atom in the equatorial position.3.The cyclohexene ring is in the boat conformation in the anhydrides of the syn-cisΔ4-octalin-1,2-dicarboxylic acids and the corresponding lactones.

Use of1H and13C NMR spectroscopy to determine the stereochemistry of 1 - methyl- δ4-octalin- 1,2-dicarboxylic acids and their derivatives

The combined use of the1H and13C NMR spectra makes it possible to unequivocally assign 1-methyl-Δ4-octalin-l,2-dicarboxylic acids and their derivatives to the proper steric series.

Use of1H and13C NMR spectroscopy to determine the stereochemistry of 1,4,5-trime thyl-4-cyclohexene-1,2-dicarboxylic acids and their derivatives

The combined use of the1H and13C NMR spectra makes it possible to unequivocally assign the 1,4,5-trimethyl-4-cyclohexene-1,2-dicarboxylic acids and their derivatives to a given steric series.

Stereochemistry of aglycon obtained in enzymatic hydrolysis of panaxoside a from ginseng

1. It was established that 20S-dihydroprotopanaxatrione (Ia) and the dihydro ketone of aglycon Ae, obtained by the enzymatic splitting of panaxoside A from ginseng, are identical. 2. The dihydro-Ae ketone is stereochemically different from the ketones that are obtained from the acid hydrolysis products of dihydropanaxoside A. 3. The theory was expressed that aglycon Ae has a 17Β(H)-configuration.