L. L. Frolova

Oxidation of secondary terpene alcohols by chlorine dioxide

Secondary terpene alcohols cis- and trans-verbenol, neo-iso-verbanol, borneol, iso-borneol, and menthol were oxidized by chlorine dioxide into the corresponding ketones. It was shown that the nature of the solvent and catalyst and the structure of the starting compound, including the stereochemistry of the hydroxyl, influenced the oxidation process.

Synthesis of 1,11,11-trimethyl-3,6-diazotricyclo [6.2.1.02,7]undeca-2,6-diene and 1,15,15-trimethyl-3,10-diazotetracyclo[10.2.1.02,11.04,9]pentadeca-2,4(9),5,7,10-pentaene from camphoroquinone enantiomers

Optically active camphordihydro-2,3-pyrazine and camphorquinoxaline were prepared from camphoroquinone enantiomers. It was shown that (1S,4R)-(+)-camphoroquinone was formed by oxidation of (1S,3R, 4R)-(−)-3-bromocamphor and (1R,4S)-(−)-camphoroquinone from (1R,3S, 4S)-(+)-3-bromocamphor, respectively. Camphor anhydride was a side product (6–10%) of the reaction.

New unsymmetrical salen-type ligand from enantiomerically pure 2-hydroxypinan-3-one

The reaction of enantiomerically pure (–)-2-hydroxypinan-3-one with ethylenediamine was studied. Depending on the reagent ratio, the reaction can afford either mono- or bis-Schiffs bases. The enantiomerically pure unsymmetrical terpenoid salen-type ligand was prepared by the reaction of 3-[(2-aminoethyl)imino]pinan-2-ol with salicylaldehyde.

Synthesis of Chiral Hydroxythiols Based on Oxygen-Containing α- and β-Pinene Derivatives

Isomeric 10-thiopinan-3-ols including (1S,2S,3S,5R)-6,6-dimethyl-2-(sulfanylmethyl)bicyclo[3.1.1]heptan-3-ol were synthesized for the first time from oxygen-containing α- and β-pinene derivatives.

New chiral cyclopalladated complexes based on the pinane and bornane imines

Abstract2α-Hydroxypinan-3-one imino derivatives react with lithium tetrachloropalladate to form palladacycles, while similar bornane derivative undergo cyclopalladation only when treated with palladium acetate.

Oxidation of terpenoid diols with chlorine dioxide. Easy preparation of α-hydroxyketones

Oxidative dehydrogenation of vicinal diols of bornane and pinane type with chlorine dioxide in dimethylformamide has yielded α-hydroxyketones with high selectivity. 3α-Hydroxy-10β-pinane-4-one has been prepared for the first time with yield of 63–65%; the product structure has been confirmed by X-ray diffraction studies.

Oxidation of terpenoid diols with chlorine dioxide: Preparation of ketols and α-chlorohydroxyketones of carane and pinane structures

Vicinal terpenoid diols of carane- and pinane-type structures have been oxidized with chlorine dioxide in pyridine to form the corresponding ketols in the preparative yield of 52–72%, the selectivity of α-hydroxyketones formation being 80–90%. It has been shown that the diols reactivity towards oxidation with ClO2 depends mainly on the stereochemistry of hydroxy groups. The catalysts, VO(acac)2, Mo(CO6), and MoCl5 have practically no effect on the oxidation process. When the reaction has been performed in dimethylformamide, the hydroxyketone chlorination occurred at high conversion.

Heterocyclization of 3-aminocamphor and 3-aminoisoborneol derivatives with cyclic β-diketones and formaldehyde. Synthesis of optically active 1,2,3,4-tetrahydroquinoline derivatives with terpene substituents

Spirocyclic 1,2,3,4-tetrahydroquinoline derivatives were prepared in quantitative yield by three-component condensation of dimedone or Meldrum’s acid with formaldehyde and (1S,3R,4S)-1,7,7-trimethyl-3(arylamino)bicyclo[2.2.1]heptan-2-one or (1S,2S,3R,4S)-1,7,7-trimethyl-3-(arylamino)bicyclo[2.2.1]heptan2-ol.

Carane amino alcohols as organocatalysts in asymmetric aldol reaction of isatin with acetone

Carane-derived β-amino alcohols with amino and hydroxy groups at positions 3 and 4 differing in their mutual arrangement and configuration were synthesized. Their application as organocatalysts in the asymmetric aldol reaction of isatin with acetone allowed one to obtain adducts with up to 84% enantiomeric excess.

STEREOSELECTIVE SYNTHESIS OF CARANE-TYPE HYDROXYTHIOLS AND DISULFIDES BASED ON THEM

Isomeric 10-sulfanylcaran-4-ols and 4-sulfanylcaran-3-ols were synthesized and used to prepare disulfides in high yields.