Search

[Display omitted] Based on a combination of quantum chemistry and atom–atom potentials methods, we developed a technique for modeling the structure and estimating the complexation energy of a binary organic complex in gas and crystal phases. The efficiency of this technique was illustrated by an example of the benzotrifuroxan–benzene molecular complex. For both phases, the same molecular binary structure (π-stacking) was obtained with a parallel arrangement of the planes of BTF and benzene molecules and complexation energies of −11.9 and −11.7 kcal mol−1 for a gas phase and a crystal cluster, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Reactions of 4-bromo-5-nitrophthalonitrile (BNPN) with enolates of alkyl 4-R-2,4-dioxobutanoates gave alkyl 3-acyl-5,6-dicyanobenzofuran-2-carboxylates, 4-(2-R-2-oxoethyl)-5-nitrophthalonitriles, or 3-acyl-1,2-benzoxazole-5,6-dicarbonitriles. With a base, 4-(2-R-2-oxoethyl)-5-nitrophthalonitriles either undergo nitro-nitrite rearrangement resulting in 3-acyl-1,2-benzoxazole-5,6-dicarbonitriles or yield 2-R-benzofuran-5,6-dicarbonitriles with a nitro group displacement. [Copyright &y& Elsevier]

Abstract: Pentathiepinopyrroles reacted with methyl propiolate and triphenylphosphine to give regioselectively dithiinopyrroles in agreement with the electron distribution in the proposed reaction intermediate. Thieno[2,3-f][1,2,3,4,5]pentathiepin when treated with methyl propiolate and triphenylphosphine gave a pair of regioisomers where the higher yielding regioisomer contained the same mode of junction as in the case of pentathiepinopyrroles. X-ray crystal structures are provided for the thieno[2,3-b][1,4]dithiine carboxylate isomers. Quantum-chemical calculations B3LYP/6-31G(d) and B3LYP/6-311++G(d,p) have been carried out for better understanding of the reaction mechanisms; the index of synchronism of the S h addition and the index of a relative difference in bond orders in transition states are in good agreement with the formation of the regioisomers by the reaction of unsymmetrical pentathiepins with alkynes containing one electron-withdrawing group. [Copyright &y& Elsevier]