Synthesis and thermolysis of the 2,3-dihydro-1H-pyrole-2,3-diones, pseudopericyclic reactions of formyl(N-phenylimidoyl)ketene: Experimental data and PM3 calculations.

The reactions of the 2,3-dihydro-1H-furan-2,3-dione 1 with Schiff bases 2a-f at 60-70 degrees C furnish the corresponding 2,3-dihydro-1H-pyrole-2,3-diones 3a-f. The heating of 3a-d afforded the corresponding 4-methoxybenzoyl(N-arylimidoyl)ketenes 4a-d as intermediates which undergo a very facile cyclization to quinoline-4-ones 5a-d. According to our PM3 calculations, fragmentation of 4-formyl-2,3-dihydro-1H-pyrole-2,3-dione and 1,4-cyclization of formyl(N-phenylimidoyl)ketene IN1 to azetin-2-one IN2 and oxetone IN3 are pseudopericyclic reactions with two orbital connections, proceed via planar transition structures. Due to to the possibility of syn and anti conformations of the imine phenyl, there are eight E/Z-isomers of IN1. In addition, we have also calculated reaction mechanism of formation of quinoline-4-ones by the PM3 method

Conformation depends on 4D-QSAR analysis using EC-GA method: pharmacophore identification and bioactivity prediction of TIBOs as non-nucleoside reverse transcriptase inhibitors

The electron conformational and genetic algorithm methods (EC-GA) were integrated for the identification of the pharmacophore group and predicting the anti HIV-1 activity of tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepinone (TIBO) derivatives. To reveal the pharmacophore group, each conformation of all compounds was arranged by electron conformational matrices of congruity. Multiple comparisons of these matrices, within given tolerances for high active and low active TIBO derivatives, allow the identification of the pharmacophore group that refers to the electron conformational submatrix of activity. The effects of conformations, internal and external validation were investigated by four different models based on an ensemble of conformers and a single conformer, both with and without a test set. Model 1 using an ensemble of conformers for the training (39 compounds) and test sets (13 compounds), obtained by the optimum seven parameters, gave satisfactory results (R-training(2) = 0.878, R-test(2) = 0.910, q(2) = 0.840, q(ext1)(2) = 0.926 and q(ext2)(2) = 0.900)

REACTION OF N-(AMINOAMIDINO)THIOUREA DERIVATIVES WITH DIMETHYLACETYLENE DICARBOXYLATE

Dimethyl acetylenedicarboxylate (DMAD) has been used in numerous heterocyclicarrangements and considered as an essential building in a natural union. In this work, ashort and productive one-pot reaction of 4-isothiazolidine-5-ylidene acetic acidderivation is described. A green and effective technique for the a mixture of more up todate 4-isothiazolidine-5-ylidene acetic acid derivation (IHB 1-16, yield 38-85%)N-(arylideneamino)-N-(arylthiocarbamyl) guanidine (AGII 1- 22) withdiethylacetyylenedicarboxylate has been created in methanol by refluxing. We wouldlike to investigate the synthesis of thiazoline compounds from thiocarbamoyl guanidinesderivatives possessing N-H groups and S=C bond which react with DMAD to givehighly functionalized 4- oxothiazolidin-5-ylidene acetate derivatives. In this reaction,both sulfur group and amino group are capable to react with DMAD. It was found thatthiourea react with DMAD exclusively with sulfur atom. The structure of the newcompounds was established by IR and NMR spectroscopy</p

Norcaradiene-cycloheptatriene substituted in position 7: Investigation of the valence isomerization equilibrium

The valence isomerism of a series of noncaradiene-cycloheptatriene compounds is investigated. Geometry and energy calculations allow to explain the nature of the transitions. Peculiarities of equilibrium shifts between different structures depending on the substituent at position 7 (X = CH3, NH2, CHO, CN) are discussed. The nature of the interaction between the substituent X and the ring (sigma- or pi-interaction) is investigated

A new method for the preparation of pyridazine systems: Experimental data and semiempirical PM3 calculations

The reactions of 4-benzo3,1-5-phenyl-2,3-furandione (1a) and 4-(4-methoxybenzoyl)-5-(4-methoxyphenyl)2.3-furandione (1b) with acyl hydrazines (2) (namely hydrazides) are reported. From these reactions, novel pyridazinone systems (3a-g) are obtained as well as the cyclization product of 3g at high temperature (4). The electronic properties and conformational parameters for these molecules, such as bond lengths, bond angles, torsion angles and atom charges, are calculated with a semiempirical PM3 method. In order to determine the mechanism of the reaction between the model furandion (R1) and formic hydrazide (R2), the electronic properties, conformational parameters and imaginary frequencies of the reactants, transition states and intermediates are calculated at the same level of theory as well