A Divergent Synthesis of Substituted 2-Aminoimidazoles from 2-Aminopyrimidines
摘要:
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-broinocarbonyl compounds 2, Using conventional heating or microwave irradiation. Thus, the cleavage of 1,2,3-substituted imidazo[1,2-a]pyrimidin-1 -iumsalts 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.
Efficient One-Pot, Two-Step, Microwave-Assisted Procedure for the Synthesis of Polysubstituted 2-Aminoimidazoles
作者:Denis S. Ermolat'ev、Eugene V. Babaev、Erik V. Van der Eycken
DOI:10.1021/ol062421c
日期:2006.12.1
A microwave-assisted, one-pot, two-step protocol was developed for the construction of polysubstituted 2-aminoimidazoles. This process involves the sequential formation of imidazo[1,2-a]pyrimidinium salts from readily available 2-aminopyrimidines and alpha-bromocarbonyl compounds, followed by opening of the pyrimidine ring with hydrazine. [reaction: see text]