Synthesis of 5-substituted 3-amino-1H-pyrazole-4-carbonitriles as precursors for microwave assisted regiospecific syntheses of pyrazolo[1,5-a]pyrimidines.
A simple route to 3-oxoalkanonitrile 5, aprecursor of the title compounds is described. Reaction of enaminones 2 with hydroxylamine hydrochloride in ethanol yielded aldoximes 3 that were converted readily into 5 in basic medium. This method has been successfully applied with a number of substrates and resulted in excellent yields of the products. Reacting 5 with trichloroacetonitrile afforded 3-amino-2-aroyl-4,4,4-trichloro-2-butenenitriles 6 that condensed with hydrazines to yield 3-amino-1H-pyrazole-4-carbonitrilederivatives 8. Substituted pyrazolo[1,5-a]pyridmidines have been prepared with regioselective condensation reactions of 8 with nonsymmetrical dielectrophiles. The structures of compounds obtained were deduced based on (1)H-NMR, (1)H-(15)N HMBC- measurements.
Al-Qalaf
Fawzia
F
Applied Science Department, College of Technological Studies, Public Authority for Applied Education and Training, Safat, Kuwait. manalabbas@hotmail.com
Mandani
Faisal
F
Abdelkhalik
Mervat Mohammed
MM
Bassam
Abeer Abdulrahman
AA
D000081:Acetamides / Q000737:chemistry*; D000473:Alkanes / Q000138:chemical synthesis*; D006993:Hypnotics and Sedatives / Q000138:chemical synthesis* / Q000737:chemistry; D008872:Microwaves; D009570:Nitriles / Q000138:chemical synthesis*; D011720:Pyrazoles / Q000737:chemistry*; D011743:Pyrimidines / Q000138:chemical synthesis* / Q000737:chemistry
D000081:Acetamides; D000473:Alkanes; D006993:Hypnotics and Sedatives; D009570:Nitriles; D011720:Pyrazoles; D011743:Pyrimidines; C031280:pyrazole; C085665:zaleplon