First example of the groebke mcr using hydoxybenzal dehydes and substituted 2‐aminopyrimidines

Abstract

2 20 o C, H +A three component condensation of 2-aminopyrimidines, isocyanides and 4-hydroxybenzaldehydes was studied. 3-Amino-2-(4-hydroxyphenyl)imidazo[1,2-a]pyrimidine derivatives were obtained in moderate yields. Using 4-hydroxy-3,5-dimethoxybenzaldehyde and 2-aminopyrimidine as starting materials in the condensation led to mixtures of isomeric 2-and 3-aminoimidazo[1,2-a]pyrimidines. It was demonstrated, that the regiospecificity of this reaction is mainly defined by the steric hindrance of substituents on the pyrimidine nucleus and the carbonyl activity of the corresponding aldehydes.

The Groebke‐Blackburn‐Bienaymé Reaction

“…All the solvents used in the GBB-3CR. ,26-28,30,39,45,51,54-56,61,66,68,74,75,78,87,96-100,103,108,110,118,120,123, 51 1:1 EtOH:H 2 O [165,180] 2125,126,128,130,136,141,142,150,153,154,156,[166][167][168]177,181,[183][184][185]187,188] …”

Synthetic approaches and functionalizations of imidazo[1,2-a]pyrimidines: an overview of the decade

“…Compound 11 and 12 were further reacted with different isocyanides to afford respective 2-aryl-3-aminosubstituted imidazo [1,2-a]pyrimidine 13 in 26-39% yields and 3-aryl-2aminosubstituted imidazo[1,2-a]pyrimidine 14 in 15% yield (Scheme 5). 24 Synthesis of imidazo[1,2-a]pyrimidine 15 in 58% yield has been achieved through microwave assisted multicomponent reaction of 2-aminopyrimidine with benzaldehyde and cyclohexyl isocyanide in the presence of recyclable montmorillonite under solvent free conditions for 3.5 min (Scheme 6). 25 Scheme 2 MCR with aryl isonitriles.…”

Groebke‐Blackburn‐Bienaymé Multicomponent Reaction Catalysed by Reusable Brønsted‐Acidic Ionic Liquids

“…In general, GBB reactions can be efficiently catalysed by different Lewis acids such as Sc(OTf) 3 , [19][20][21][22][23] Yb(OTf) 3 , [24][25][26] In(OTf) 3 , [27][28][29][30] Gd(OTf) 3 , [31] InCl 3 , [32] BiCl 3 , [33,34] RuCl 3 , [35] FeCl 3 , [36] ZnCl 2 , [37] ZrCl 4 , [38,39] CeCl 3 .7H 2 O, [40] and LaCl 3 .7H 2 O, [41] among others. In addition, the use of ordinary Brønsted acids, such as HClO 4 , [42][43][44] PTSA, [45,46] AcOH, [47,48] HCl, [49,50] TFA, [51] NH 4 Cl, [52] ClCH 2 CO 2 H, [53] as well as SiO 2 /H 2 SO 4 , [54] are also reported in the literature.…”