Four‐component tandem reaction to synthesize dihydrotetrazolopyrimidinyl carbamides

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Four-component tandem procedure to prepare a series of dihydrotetrazolopyrimidinyl carbamides starting from diketene, amine, 5-aminotetrazole, and aldehyde was newly developed in the presence of iodine. Most of the products were obtained in moderate to good yield after simple workup of the final reaction mixture, the scope and limitation was also probed into.

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

“…For instance, Zeng et al presented a four-component tandem procedure to prepare a series of dihydrotetrazolopyrimidinyl carbamides 60. 59 N -alkyl acetoamide 40 was generated by stirring a solution containing amines 58 and diketen 56 in ethyl acetate at room temperature for 2 h. Subsequently, the temperature was increased to 78 °C and 5-aminotetrazole 16 and aldehyde 4 were added together with iodine (30 mol%). It was observed that aryl amine did not work given that combining aniline with diketen did not afford the corresponding product even after 24 h. A similar and greener approach was introduced by A. Shaabani et al , in which 2,2,6-trimethyl-4 H -1,3-dioxin-4-one 56 was combined with different alkyl amines 58 at 150 °C for the in situ generation of N -alkyl acetoamide 40.…”

Aminoazole-Based Diversity-Oriented Synthesis of Heterocycles

“…For example, the formation of acetoacetamide building-block by synthetic methods is an expensive and difficult procedure. Therefore, to avoid laborious stage of acetoacetamide synthesis, as a continuation of the work of Shaabani et al ( 2009 ) four-component procedure for obtaining N ,7-disubstituted-5-methyl-4,7-dihydrotetrazolo[1,5- a ]pyrimidine-6-carboxamides 199 (Zeng et al, 2012 ) was elaborated. It consisted of the reaction of primary amines 198 , diketene 197 , 5-aminotetrazole ( 5b ) and aldehydes 1 (EtOAc-I 2 , Δ, 78°C, 4 h).…”

Molecular iodine-catalyzed multicomponent reactions: an efficient catalyst for organic synthesis

“…Four-component tandem procedure to prepare a series of dihydrotetrazolopyrimidinyl carbamides 108 starting from diketene, amines, 5-AT, and aromatic aldehydes was developed by Zeng et al (Scheme 39). 93 In the procedure of tandem reaction, a solution of amine and diketene was stirred in AcOEt at room temperature for 2 h. Then, the aldehyde, 5-AT and iodine were added, and the temperature was increased to 78 uC. However, the expected product was not detected in the final mixture in the case of anilines or aliphatic aldehydes.…”