874773-92-9Relevant academic research and scientific papers
Regioselective synthesis of 1- and 4-substituted 7-oxopyrazolo[1,5-a]pyrimidine-3-carboxamides
Drev, Miha,Gro?elj, Uro?,Mevec, ?pela,Pu?avec, Eva,?trekelj, Janja,Golobi?, Amalija,Dahmann, Georg,Stanovnik, Branko,Svete, Jurij
, p. 8267 - 8279 (2014)
The synthesis of 7-substituted pyrazolo[1,5-a]pyrimidine-3-carboxamides was studied. First, methyl 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (5) was prepared in three steps from methyl 5-amino-1H-pyrazole-4-carboxylate (3). Treatment of 5 with POCl3 gave the highly reactive 7-chloro derivative 10, which was reacted with amines, benzyl alcohol, and phenylboronic acid in the presence of Pd-catalyst to give the corresponding 7-substituted derivatives 11. Hydrolysis of the esters 5 and 11 followed by amidation gave the corresponding carboxamides 16a-h and 15. Regioselectivity of N-alkylation of 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylic acid derivatives 5 and 16 was tunable by the carboxy function. Alkylation of the secondary amides 16a-f furnished the 1-alkyl derivatives 17a-f, whereas the ester 5 and the tertiary amides 16g,h gave the 4-alkyl derivatives 14a-d and 16m,n, selectively.
