Effect of high pressure on the composition of stereoisomers of the Diels-Alder reaction between furan and maleic anhydride

The kinetic data on the Diels-Alder reaction between furan and maleic anhydride at atmospheric pressure and 20 and 40°C correspond to a scheme of the process which includes transformation of an endo-isomer into an exo-isomer without preliminary decomposition into the starting substances. The reaction is significantly accelerated by an increase in the pressure, and the rate of formation of the exo-isomer is close to the rate of formation of the endo-isomer both at atmospheric and at high pressure. The endo-isomer is obtained with a high yield (up to 45%) at a high pressure, and this permitted determining the rate constant of its decomposition at atmospheric pressure.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2510–2517, November, 1989.     

13C and1H NMR spectra and stereoconfiguration of 1,4-adducts of the Diels-Alder reaction of furan with methyl acrylate and maleic anhydride

¹³C and¹H NMR spectra were taken for the 1,4-adducts of furan with methyl acrylate and maleic anhydride. The¹³C chemical shifts are characteristic: these values for C¹, C³, and C⁶ (adducts (I) and (II)) and C¹, C⁴ C², C³, C⁵, and C⁶ (adducts (III) and (IV)) depend on the orientation of the substituent at C² in the case of methyl acrylate and at C² and C³ in the case of maleic anhydride and may be used for the assignment of the adducts to the endo and exo isomers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1669–1671, July, 1990.     

Pheromones of coleoptera Communication 4. Synthesis of multistriatin with the application of the thermal hydroxy-cope rearrangement under high pressure

Conclusion The synthesis of multistriatin (in the form of the , , and isomers) was accomplished in three stages from 2-methyl-1-penten-3-one (IV) with the total yield of 13%. The thermal hydroxy-Cope rearrangement of 3-ethyl-2-methyl-1,5-heptadien-3-ol (II) at the pressure of 10 kbar was utilized at the key stage of the synthesis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2776–2780, December, 1986.     

Synthesis of 5-ketotetrazoles under high pressure

Conclusions The reaction of -ketonitriles with hydrazoic acid and organic azides at high pressure is an effective method for the synthesis of 5-acyltetrazoles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1168–1170, May, 1988.     

Effect of high pressure on the rate constant of the Diels-Alder reaction between furan and maleic anhydride

The effect of high pressure (up to 700 MPa) on the rate of the Diels-Alder reaction between furan and maleic anhydride has been investigated in deuterated acetone at 20C. The volume effect of the reaction at atmospheric pressure is found to be V₀=–28.0 cm³/mole. The rate constants for the formation, decomposition and isomerization of the products have been found by numerical integration. The volume of activation V in the pressure range studied has been determined from the observed dependence of log k upon P by spline approximation and was found to be –30.5 cm³/mole at atmospheric pressure, close to the volume change in the reaction, which is consistent with the assumption of a conjugated cyclic transition state.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 525–529, March, 1990.     

Synthesis of p38 MAP kinase inhibitor BIRB 796 and analogs via copper-mediated N-arylation reaction

Direct N-arylation of urea (5) with various arylboronic acids mediated by cupric acetate furnished BIRB796 and a range of N-substituted BIRB796 analogs in good to moderate yields in one step. Urea (5) was readily synthesized from commercially available compounds.