A rapid regioselective C3-functionalization of 7-phenylpyrazolo[1,5-a]pyrimidines: en route to the synthesis of zaleplon and reversan drugs.

A facile and sustainable strategy for the C3-functionalization of 7-phenylpyrazolo[1,5-a]pyrimidines, under mild and environmentally benign conditions using copper cyanide as the cyanating agent, has been developed. This protocol demonstrates broad functional group tolerance, affording the products in good to excellent yields and enabling gram-scale synthesis. A diverse array of synthetic transformations is divulged via amidation, hydrolysis, reduction and esterification, emphasizing the method's utility in the post-functionalization process and in building organic frameworks. In addition, this method is also applied for the concise synthesis of the hypnotic drug zaleplon and the MRP1 inhibitor reversan.