Triterpenoids from plants of the genus Tamarix

The taraxeran-14-ene-type triterpenoids methyl 3-β-al-D-fridoolean-14-en-28-oate (1), 3-α-[3″,4′-dihydroxytrans-cinnamoyl]-oxy-D-fridoolean-14-en-28-oic acid (2), and β-sitosterol (3) were isolated from the aerial part of plants from the genus Tamarix (T. laxa, T. elongata) (Tamaricaceae). The structures of the triterpenoids were proved using spectral data (IR, UV, PMR, ¹³C NMR, 2D NMR ¹H-¹H COSY, HMQC, HMBC, mass). Compound 1 is new and not previously described in the literature. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 271–273, May–June, 2006.     

13C NMR Spectra of polycyclic compounds: spiro(bicyclo[2.2.1]heptane-7,1′-cyclopropane) derivatives

The¹³C NMR spectra of 15 spirocyclopropane derivatives in the (C⁷)-norbornane series have been investigated, signal assignments made, and the stereochemistry of isomeric products has been determined. It was found that the methylene group signals in the cyclopropane fragment may be used as criteria in making the stereochemical assignments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 555–559, March, 1990.     

New One-Pot Synthesis of Polysubstituted Benzofurans and Benzo-1,4-dioxines

It has been revealed that the copper(II) triflate catalyzed reaction of ethyl-2-diazo-3-oxobutanoate with phenols followed by cyclization of the intermediate enol in the presence of polyphosphoric acid is a simple and efficient method of synthesis of polysubstituted benzofurans. The use of pyrocatechol leads to the corresponding substituted 1,4-benzodioxine-2-carboxylates as major products.     

Catalytic cyclopropanation of stereoisomeric 1,3-dichloropropenes with methyl diazoacetate

The catalytic cyclopropanation of cis- and trans-1,3-dichlorpropenes with methyl diazoacetate in the presence of a copper catalyst was studied. The products composition and ratio were shown to depend on the spatial structure of 1,3-dichloropropene.     

Antioxidant Activity of 2-Aminothiazoles Containing a Diterpene Fragment in the Model System of the Liquid-Phase Radical-Chain Oxidation of 1,4-Dioxane

The antioxidant activity of 2-aminothiazoles containing a diterpene fragment in a model system of initiated radical-chain oxidation of 1,4-dioxane was evaluated. The compounds exhibited different inhibitory activities depending on their structure. The effective rate constant of the interaction of substituted 2-aminothiazoles with the 1,4-dioxane peroxyl radical was measured. 2-Aminothiazoles obtained by the chemical transformations of maleopimaric acid N-phenylamide showed higher reactivity with the peroxyl radical.     

Low-temperature specific heat of TlCrS2

The specific heat of the ferromagnetic semiconductor TlCrS₂ is investigated experimentally, and the thermodynamic parameters are calculated. It is demonstrated that the temperature dependence of the magnetic specific heat of the TlCrS₂ compound is characteristic of quasi-two-dimensional magnetic systems.     

Reaction of Methyl Diazoacetate with Amines Catalyzed by Ru<Subscript>2</Subscript>(OAc)<Subscript>4</Subscript>Cl

Reactions of primary and secondary amines with methyl diazoacetate in the presence of Ru₂(OAc)₄Cl gave the corresponding N-substituted glycine methyl esters in almost quantitative yield. Catalytic decomposition of methyl diazoacetate generates methoxycarbonylcarbene which is inserted into the N-H bond of amines with high regioselectivity.