The gold–acid‐co‐catalyzed synthesis of nine series of fused azaheterocycles with structural diversity starting from the same synthons as readily available propargylic hydroperoxides and aromatic amines has been achieved. The overall tandem process consists in a gold‐catalyzed hydroperoxide rearrangement/Michaelreaction followed by a final acid‐catalyzed cyclization.
Highly facile and regio-selective synthesis of pyrazolo[1,5-a]pyrimidines via reactions of 1,2-allenic ketones with aminopyrazoles
作者:Xinying Zhang、Yunping Song、Lin Gao、Xiaojie Guo、Xuesen Fan
DOI:10.1039/c3ob42445f
日期:——
An efficient procedure for the syntheses of pyrazolo[1,5-a]pyrimidines through reactions of 1,2-allenic ketones with aminopyrazoles under extremely mild conditions without using any catalyst or promoter has been developed. The reactions showed excellent regio-selectivity with all the allenic ketone substrates except for those bearing an alkyl group at the internal position of the allene moiety. The reason behind this regio-selectivity dissimilarity has been explored with the aid of the B3LYP/6-31G* level of density functional theory. Moreover, this novel procedure has been successfully applied in the preparation of nucleoside-pyrazolo[1,5-a]pyrimidine chimeras with potent antiviral activities.