Rearrangement of thiazolo[3,2-a]pyrimidines into triazolo[4,3-a]pyrimidines induced by C=N bond reduction

Synthesis, Self-Assembly in Crystalline Phase and Anti-Tumor Activity of 2-(2-/4-Hydroxybenzylidene)thiazolo[3,2-a]pyrimidines

“…All arylmethylidenethiazolopyrimidines 7-15 were synthesized following the scheme presented on Figure 2. In the first stage, a three-component Biginelli condensation involving appropriate aldehyde (benzaldehyde, 2-methoxybenzaldehyde, 4-methoxybenzaldehyde, 3-nitrobenzaldehyde, or 4-brombenzaldehyde), thiourea, and 1,3-dicarbonyl compound (acetoacetic ether or benzoylacetone) in a molar ratio 1:1.5:1 led to the preparation of 1,2,3,4-tetrahydropyrimidine-2-thions in the presence of a catalytic amount of molecular iodine (0.03 mmol) under refluxing conditions in acetonitrile as described earlier [18][19][20][21][22]. Then the obtained compounds were used as precursors for the synthesis of targeted 2-and 4-hydroxybenzylidene thiazolo[3,2-a]pyrimidine 7-15 by reaction with corresponding 2-or 4-hydroxybenzaldehydes.…”

“…All reagents (Acros Organics (Belgium), Alfa Aesar (USA)) were used without further purification. The 1,2,3,4-tetrahydropyrimidine-2-thions [22][23][24][25][26]…”

“…All reagents (Acros Organics (Belgium), Alfa Aesar (USA)) were used without further purification. The 1,2,3,4-tetrahydropyrimidine-2-thions [22][23][24][25][26], ethyl (Z)-2-(2-hydroxybenzylidene)-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 7 [17], ethyl (Z)-2-(4-hydroxybenzylidene)-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-thiazolo[3,2-a] pyrimidine-6-carboxylate 13 [30], ethyl (Z)-2-(2-hydroxybenzylidene)-5-(4-methoxyphenyl)-7-methyl-3-oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 8 [17] and ethyl (Z)-2-(2-hydroxybenzylidene)-5-(2-methoxyphenyl)-7-methyl-3-oxo-2,3-dihydro-5H-thiazolo[3,2a]pyrimidine-6-carboxylate 9 [17] were synthesized according reported methods.…”

Different Synthetic Methods for the Preparation of Triazolopyrimidines and their Biological Profile

“…Lashmanova et al [118] . developed a new method for the preparation of 3‐(hydroxymethyl)‐[1,2,4]‐triazolo[4,3‐ a ]pyrimidines 159 (49–77 %) based on the reduction of 2‐(arylhydrazinylidene)‐3‐oxo‐[1,3]‐thiazolo[3,2‐ a ]pyrimidines with NaBH 4 in the presence of V 2 O 5 at room temperature (Scheme 108).…”

“…Lashmanova et al [118] developed a new method for the preparation Appna et al [119] synthesized a series of novel [1,2,4]triazole fused pyrido [2,3-d] ). [120] The isomer 161 is namely formed due to cyclization through the least sterically hindered position.…”