Simple approach to the synthesis of 3-fluoro pyrazolo[1,5-a]pyrimidine analogues

Abstract

A simple method for the synthesis of novel 3-fluoro pyrazolo[1,5-a]pyrimidine analogues has been developed starting from fluoro acetonitrile and benzoyl chloride. The desired compounds are synthesized from a 3-amino-4-fluoro pyrazole intermediate. The versatility of the approach was demonstrated by the synthesis of a small library of pyrazolo [1,5-a]pyrimidine.

Heterocyclizations of β-alkoxy, β-diaminoalkyl, and related β-functionalized enones (enals) with NCN-binucleophiles

“…In turn, most of the known transformations relied on using enones derived from ketoesters 39 (Scheme 32) [197][198][199][200][201][202][203] that were subjected to heterocylizations with (3)5-aminopyrazoles (mostly substituted by alkyl, aryl, halogen, nitrile and nitro groups), or diazo diaminopyrazoles [204,205]. Other reported reactions included enones derived from malonates 41 [206][207][208] or cyanoacetates 36 [208][209][210][211][212][213][214], haloalkyl enones 22-24, and their analogs [206,[215][216][217][218][219][220], and functionalized derivatives bearing sulfonyl [221] or alkynyl [222] groups. Notably, in most cases, the condensation reaction proceeded in a regioselective manner.…”

Regioselective Synthesis of 7-(Trimethylsilylethynyl)pyrazolo[1,5-a]pyrimidines via Reaction of Pyrazolamines with Enynones

“…The vast majority of known methods for synthesis of pyrazolo­[1,5- a ]­pyrimidines rely on condensation of N -unsubstituted pyrazolamines with 1,3-dicarbonyl compounds or their analogues . Among such analogues, enaminones and enaminonitriles, ethoxymethylene derivatives, β-halovinyl aldehydes, and allenic ketones were employed successfully. A less obvious example is the condensation of 1,3,5-triaryl 1,5-dicarbonyl compounds with pyrazolamines, which proceeds with loss of one of the carbonyl groups .…”