5021-68-1Relevant academic research and scientific papers
Synthesis of Compounds Related to 4(5)-Aminoimidazole-5(4)-carboxamides: Part IV - Synthesis of 2-Substituted 5-Aminothiazoles and Reaction of Related Thiazolium and Imidazolium Salts with Bases
Sen, A. K.,Mukhopadhyay, Ajoy Kumar
, p. 275 - 278 (2007/10/02)
N-Cyanomethylimidates (Ia-e) have been reacted with H2S in pyridine.While ethyl N-(ethoxycarbonylcyanomethyl)acetimidate (Ia), ethyl N-(carbamoylcyanomethyl)acetimidate (Ib) and ethyl N-(carbamoylcyanomethyl)benzimidate (Ic) furnish varying amounts of a mixture of ethyl 5-amino-2-methylthiazole-4-carboxylate (IIIa) and ethyl 2-methyl-4(5)-mercaptoimidazole-5(4)-carboxylate (IVa) (in 2:1 ratio), 5-amino-2-methylthiazole-4-carboxamide (IIIb) and 2-methyl-4(5)-mercaptoimidazole-5(4)-carboxamide (IVb) (in 1:1 ratio) and 5-amino-2-phenylthiazole-4-carboxamide (IIIc) and4(5)-mercapto-2-phenylimidazole-5(4)-carboxamide (IVc) (in 1:5 ratio) respectively, the corresponding formimidates (Id,e) furnish the corresponding thiazole derivatives, ethyl 5-aminothiazole-4-carboxylate (IIId) and 5-aminothiazole-4-carboxamide (IIIe) as the sole products.Reaction of ethyl oximinocyanoacetate (VI) with H2S in pyridine in the presence of ethyl orthoformate, however, produces only the imidazole derivative, ethyl 4(5)-mercaptoimidazole-5(4)-carboxylate (IVd).The changing pattern of the products is interpreted in terms of the formation of thiol and thioamide intermediates.Treatment of 5-amino-1-benzyl-4-carboxamido-2,3-dimethylimidazolium toluene-p-sulphonate and 5-amino-4-carboxamido-1,2,3-trimethylimidazolium toluene-p-sulphonate with aq.NaOH or NaOEt in EtOH effects dequaternization to regenerate 5-amino-1-benzyl-2-methylimidazole-4-carboxamide and 1,2-dimethyl analogue respectively, while the 5-amino-4-ethoxycarbonyl-2,3-dimethylthiazolium toluene-p-sulphonate decomposes on warming with NaOEt in EtOH.
