Ermolat'ev Denis S, Van der Eycken Erik V
Laboratory for Organic & Microwave-Assisted Chemistry, Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
J Org Chem. 2008 Sep 5;73(17):6691-7. doi: 10.1021/jo8008758. Epub 2008 Jul 26.
A new divergent and efficient synthesis of substituted 2-aminoimidazoles 5 and 6 has been developed starting from the readily available 2-aminopyrimidines 1 and alpha-bromocarbonyl compounds 2, using conventional heating or microwave irradiation. Thus, the cleavage of 1,2,3-substituted imidazo[1,2-a]pyrimidin-1-ium salts 4 with hydrazine or secondary amines led to 1,4,5-trisubstituted 2-aminoimidazoles 5, when the hydrazinolysis of 2-hydroxy-2,3-dihydro-1H-imidazo[1,2-a]pyrimidin-4-ium salts 3, followed by a novel Dimroth-type rearrangement, resulted in formation of 2-amino-1H-imidazoles 6. The relevant pathway of transformations was identified by characterization of the intermediates.
从容易获得的2-氨基嘧啶1和α-溴代羰基化合物2出发，利用常规加热或微波辐射，已开发出一种新型的、高效的合成取代2-氨基咪唑5和6的方法。因此，当2-羟基-2,3-二氢-1H-咪唑并[1,2-a]嘧啶-4-鎓盐3经肼解，随后进行一种新型的Dimroth型重排，生成2-氨基-1H-咪唑6时，用肼或仲胺裂解1,2,3-取代的咪唑并[1,2-a]嘧啶-1-鎓盐4会得到1,4,5-三取代的2-氨基咪唑5。通过对中间体的表征确定了相关的转化途径。
