A short synthesis of 4-substituted 1-(hydroxyalkyl)-1H-pyrazolo[3,4-d]pyrimidines (original) (raw)

One-pot, four component synthesis of pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidines derivatives

2018

A green approach to synthesis of the polyfunctionalized pyrazole [4′,3′:5,6]pyrido[2,3-d] pyrimidines derivatives was successfully achieved via one-pot, four component reactions of β-aminocrotonitrile, phenyhydrazine, arylglyoxals, barbituric acid derivatives in the presence of TEA (Triethylamine) as a catalyst in water under the reflux conditions. This protocol provided mild reaction conditions, short reaction times, high yields, low cost, easy isolation of products and possible biological, and pharmaceutical activities.

A Novel Two Step Synthesis of 3,4-Dihydro-4-oxo-5H-pyrano[2,3-d]pyrimidines

HETEROCYCLES, 2006

A novel two step synthesis of 5,7-diaryl-3,4-dihydro-4-oxo-5Hpyrano[2,3-d]pyrimidines has been reported based on condensation of 2thiobarbiturates with chalcones followed by reductive desulfurization of 5,7diaryl-1,2,3,4-tetrahydro-4-oxo-2-thioxo-5H-pyrano[2,3-d]pyrimidines with nickel boride. Pyrans 1 and pyrimidines 2 individually or in combination possess significant biological activity such as antiallergic, analgesic, sedative and antiphlogistic. Some of the derivatives of pyrimidines also show herbicidal and inseticidal properties. Different routes have been described in literature for the synthesis of pyrano[2,3-d]pyrimidines 3 as well as 2-oxo and 2-thioxo analogues of 1,2,3,4-tetrahydro-4-oxo-5Hpyrano[2,3-d]pyrimidines. 4,5 Unlike the synthesis of 2-oxo and 2-thioxo analogues, synthesis of 3,4dihydro-4-oxo-5H-pyrano[2,3-d]pyrimidines has not received any attention. Thus there is sufficient scope for the development of new, efficient and practical protocols for the synthesis of 3,4-dihydro-4oxo-5H-pyrano[2,3-d]pyrimidines. We have attempted to achieve the desired synthesis by addition of 2thiobarbiturates to different chalcones to give 5,7-diaryl-1,2,3,4-tetrahydro-4-oxo-2-thioxo-5Hpyrano[2,3-d]pyrimidines followed by reductive desulfurization with nickel boride which has been reported as a reducing 6 and dethiating 7 agent by our group. We report herein a convenient and efficient synthesis of 3,4-dihydro-4-oxo-5H-pyrano[2,3-d]pyrimidines (4a-f) and of 1,2,3,4-tetrahydro-4-oxo-5H-pyrano[2,3-d]pyrimidines (5g-h) in two steps. Thus 2-thioxo-5Hpyrano[2,3-d]pyrimidines (3a-h) were prepared by the condensation of chalcones (1a-f) with 2thiobarbituric acids (2a-b) in high yields by a reported method. 5 Though compounds (3a, 3b and 3g) are reportedly known, a number of new compounds e.g. 3c-f and 3h were characterized by NMR, IR and MS spectra. These results are listed in Table 1. Selective desulfurization of 1,2,3,4-tetrahydro-4-oxo-2-thioxo-5H-pyrano[2,3-d]pyrimidines without affecting the carbonyl group would result in the desired 3,4-dihydro-4-oxo-5H-pyrano[2,3-d]pyrimidines.

One-Pot Multicomponent Synthesis of Pyrazolo[3,4-d]pyrimidine-6-one Derivatives

Polycyclic Aromatic Compounds, 2016

An environmentally benign, simple, and efficient procedure has been developed for the one-pot multicomponent synthesis of pyrazolo[3,4d]pyrimidine-6-one derivatives by the reaction of the variety of arylaldehydes, 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, and urea in the presence of catalytic amount of poly(N-vinylpyridinium) hydrogen sulfate in glycerol. The present method affords non-toxic and noncorrosive medium, short reaction times, high yield of the products, mild reaction conditions as well as simple experimental and isolation procedures. The catalyst can be recycled by simple filtration and reused without any significant reduction in its activity.

The synthesis of new pyrazolo[1,5-a]pyrimidine derivatives

Arkivoc, 2015

A simple high-yielding procedure for the synthesis of novel pyrazolo[1,5-a]pyrimidine analogues is reported via the condensation of 1,3-diketones or keto ester with substituted 5aminopyrazoles in presence of H 2 SO 4 using AcOH as solvent.

Synthesis of some novel pyrazolo[3,4-d]pyrimidine derivatives

Arkivoc, 2007

Reaction of ethyl imidates derived from N-aryl-5-amino-4-cyanopyrazoles with amines or arylhydrazines gave only 4-substituted pyrazolo[3,4-d]pyrimidines, resulting from cyclization followed by Dimroth rearrangement. From the reaction with arylhydrazines, a mixture of the hydrazines and their oxidized forms, the azo products, was obtained. This was proven by an independent synthesis starting from the corresponding 4-chloropyrazolo[3,4-d]pyrimidines as starting material. The structures of the compounds obtained were confirmed by mass spectrometry, 1 H and 13 C NMR.