CARBO[3+3] CYCLOCONDENSATION REACTIONS. A NEW METHOD FOR THE SYNTHESIS OF TETRAHYDROPYRAZOLO[1,5-<i>b</i>]QUINAZOLINES AND TETRAHYDROPYRAZOLO[4,5-<i>b</i>]QUINOLINES
DOI:
https://doi.org/10.1007/1221Keywords:
3-R-aminopyrazoles, chalcones, partially hydrogenated pyrazolo[3, 4-b]pyridines, partially hydrogenated pyrazolo[1, 5-a]pyrimidines, 5-b]quinazolines, partially hydrogenated pyrazolo[4, 5-b]quinolines, carbo[3 3] cyclocondensation, domino reaction, regio-selective synthesisAbstract
The cyclocondensation of substituted 5-aminopyrazoles with benzylidene acetone leads to the regioselective synthesis of dihydropyrazolo[1,5-a]pyrimidines and dihydropyrazolo[3,4-b]pyridines containing a methyl group in the six-membered heterocycle. Compounds of both these groups readily undergo carbo[3+3] cyclo-condensation with chalcones in butanol under alkaline catalysis conditions and upon heating to give aryl-substituted tetrahydropyrazolo[1,5-b]quinazolines and tetrahydropyrazolo[4,5-b]quinolines. Ultrasonic initiation of these reactions leads to enhanced rate and higher yield of the desired products.
Authors: V. D. Orlov and D. Yu. Sidorenko.
English Translation in Chemistry of Heterocyclic Compounds, 2012, 48 (4), pp 650-657
