Acetic aldehyde in multicomponent synthesis of azolopyrimidine derivatives in water

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

“…Another example of a 1,3-dicarbonyl compound that often exhibits unusual behavior in the three-component synthesis of azolopyrimidines [27,29] is ethyl 4,4,4-trifluoroacetoacetate ( 13 ). In these transformations, the last reaction step, a water elimination, sometimes does not occur, and the final product is the 5-hydroxy-containing tetrahydro derivative.…”

Unusual in Water Multicomponent Reaction of 3-Amino-5-methylpyrazole, Acetylacetone and Aldehyde

“…as reagents (Scheme 2), whereas the majority of described data on azolopyrimidine synthesis presume use of exclusively aromatic aldehydes [3][4][5][6] [9,10] In the current research, we attempted to extend the application of multicomponent approach and to synthesize pyrazolo [1,5-a]pyrimidines using 3-aminopyrazole derivative and to check the scope and limitations of threecomponent in water synthesis concerning azolopyrimidines; however, our results here were somewhat unexpected.…”

“…In our recent publications [9,10] we showed a possibility of obtaining azolopyrimidine in three-component way using 3-amino-1,2,4-triazole (6) and acetylacetone 8as starting materials and water as solvent; the important feature of that research is use of formaldehyde (7a, [9]) or acetaldehyde (7b, [10])…”

α-Aminoazoles/azines: key reaction partners for multicomponent reactions

“…Using ethyl 4,4,4-triuoro-3-oxobutanoate as the 1,3-dicarbonyl compound under the same reaction conditions, the corresponding 5hydroxy-4,5,6,7-tetrahydro derivatives 34 were obtained, which failed to dehydrate at the reaction temperature (Scheme 13). 48 The simplest aldehyde, formaldehyde (in the form of paraformaldehyde) was also effectively incorporated into the structure of azole-fused pyrimidine derivatives. Specically, S. A. Komykhov et al reported a method for the preparation of 8 unsubstituted 4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines 36, which presumed the three-component reaction of 3-amino-1,2,4-triazole 25 with paraformaldehyde 35 and different 1,3dicarbonyl compounds 12 (Scheme 14).…”

“…Using ethyl 4,4,4-trifluoro-3-oxobutanoate as the 1,3-dicarbonyl compound under the same reaction conditions, the corresponding 5-hydroxy-4,5,6,7-tetrahydro derivatives 34 were obtained, which failed to dehydrate at the reaction temperature ( Scheme 13 ). 48 …”