Synthesis of Optically Active,Cyclic α‐Hydroxy Ketones and 1,2‐Diketones from Verbenone Epoxide

The reactivity of verbenone epoxide ( 5 ), a terpenoid from the pinane series, towards different aliphatic and aromatic aldehydes in the presence of natural montmorillonite (askanite–bentonite) clay has been studied. A series of mechanistically different transformations afforded a number of new, optically active, polyfunctional compounds ( 7, 8, 10 – 14, 16 ). These products are potentially interesting synthons in asymmetric synthesis.     

An investigation of the membranotropic properties of the plant toxin thionin isolated fromPyrularia pubera

It has been shown by the ESR of spin probes that thionin initially interacts with with negatively charged membranes electrostatically and then passes into the membranes to a depth comparable with the length of the hydrophobic sections of the protein loops. Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Brigham Young University, Provo, Utah, USA. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 594–597, July–August, 1993.     

Asymmetric oxidation of 4-nitro-6-trifluoromethyl-1,2,3-benzotrithiole

Both enantiomers of 4-nitro-6-trifluoromethyl-1,2,3-benzotrithiole 1-oxide as analogs of Varacins B and C were synthesized for the first time. The use of the Modena method ensures higher optical purity but lower yields of the chiral sulfoxides, as compared to the Kagan procedure.     

Complexation of lappaconitine with glycyrrhizic acid: stability and reactivity studies

NMR and UV-vis spectroscopy have been used to study the complexation of antiarrhythmic alkaloid lappaconitine with an efficient complexing agent from licorice, glycyrrhizic acid, which is known to profoundly influence the therapeutic activity of the alkaloid in the complex. In MeOH, DMSO, or aqueous solutions, lappaconitine has been shown to form a stable complex with glycyrrhizic acid with 1:1 stoichiometry over a broad concentration range from 1 microM to 300 microM. The stability constant K(11) equals 2.0 x 10(5) M(-1) in aqueous solution. A similar complex of lappaconitine hydrobromide--the pharmaceutical formulation used in the treatment of arrhythmia--is 2 orders of magnitude less stable than pure lappaconitine. A notable decrease in the rate of the photoinduced electron-transfer reaction between lappaconitine in a complex with glycyrrhizic acid and tyrosine allows the suggestion of an explicit interrelation between the suppressed chemical reactivity of the bound alkaloid and the changes of its therapeutic efficiency.     

Reactions of Some Terpenoids with CH-Acids in the Presence of Cs-β Zeolite

Reactions of some ,-unsaturated ketones from terpenoid series with CH-acids in the presence of Cs- zeolite were studied under various conditions. The variation of reaction conditions (heating, ultrasonic irradiation) strongly affected the reaction products ratio, and the effect was singular in each case and gave different results.     

Reduction of (+)-usninic acid and its pyrazole derivative by sodium borohydride

The reaction of (+)-usninic acid and its pyrazole derivative with sodium borohydride was studied. The reduction occurred stereoselectively at the endocyclic carbonyl group. Novel (+)-usninic acid derivatives that were reduction products of the carbonyls were obtained.     

One-pot synthesis of 1,5,3-oxathiazepanes via the three-component condensation of primary amines,formaldehyde and 2-mercaptoethanol

The three-component condensation reaction of primary amines, formaldehyde and 2-mercaptoethanol using salts of transition and rare earth metals as catalysts was developed to obtain a new 7-membered heterocyclic structural building block, 1,5,3-oxathiazepanes, in good to excellent yields. The structure of the heterocyclic fragment was confirmed by NMR spectroscopy.