regioselectivity

In this scientific contribution, regio- and diastereo- selectivity of [3+2] cycloaddition (32CA) of N-tert-butyl,α-(4-trifluoromethyl)-phenylnitrone (1) with methacrolein (2) were investigated using DFT method at B3LYP/6-31(d) computational level in gas and dichloromethane solvent. The molecular electrostatic potential MESP was used to show the most active centers in the examined molecules. Global and local reactivity indices as well as thermodynamic parameters have been calculated to explain the regioselectivity and stereoselectivity for the selected reaction.

N-allyl(cinnamyl)substituted derivatives of 6-methyluracil were synthesized. The reactions of their bromo- and iodocyclization were performed which led to the formation of the derivatives of dihydro¬oxazolo¬pyrimidinium and dihydrooxazinepyrimidinium. The factors that favor the regioselectivity of these reactions were suggested.

Reactions of nucleophilic substitution between 5-R-2,3-dichloro-1,4-naphthoquinones and 4-amino-5- heteryl-4H-1,2,4-triazoles-3-thiols were carried out. It is shown that the interaction can take place in two alternative ways and the reaction direction is controlled by reaction conditions. Search of differences in atoms reactivity in investigated molecules by comparing the calculated Fukui atonic indices was conducted.

It was found that 2-acylthioacetamides enter Biginelli reaction with aromatic aldehydes and urea /thiourea forming 2-oxo(thio)-N,4-diaryl-1,2,3,4-tetrahydropyrimidine-5-carbothioamides. Under the influence of K3[Fe(CN)6] in alkaline environment, the expected 2-oxo(thio)-N,4-diaryl-5-(benzothiazole-2'-yl)-1,2,3,4-tetrahydropyrimidines were not been received while 2-oxo(thio)-N,4-diaryl-1,2,3,4-tetrahydropyrimidine-5-carbamides were the products of interaction.