A SIMPLE AND PRACTICAL SYNTHESIS OF 2-AMINOIMIDAZOLES

A new and simple two-step procedure to synthesize 2-aminoimidazoles (2 -AI's) from readily available materials has been developed. The cycliz ation reaction of alpha-halo ketones and N-acetylguanidine in acetonit rile (MeCN) at reflux, or in dimethylformamide (DMF) at ambient temper ature, gives 4(5)-substituted and 4,5-disubstituted N-(1H-imidazol-2-y l)acetamides, which are then hydrolyzed to their respective 2-AI's. In general, the purified products were isolated in good yields. We have prepared several examples and have demonstrated the usefulness of this method by its application in the total synthesis of 8, an interesting histamine analog, and oroidin, 15, a marine natural product isolated from various sponges.