Concise synthesis of pyrrolo[2,3-<i>d</i>]pyrimidine derivatives via the Cu-catalyzed coupling reaction

<p>We reported a green and simple Cu-catalyzed method for the efficient synthesis of 2-chloro-7-cyclopentyl-<i>N,N</i>-dimethyl-7H-pyrrolo[2,3-<i>d</i>]pyrimidine-6-carboxamide as the key intermediate in the synthetic approaches to pyrrolo[2,3-<i>d</i>]pyrimidine derivatives from 5-bromo-2,4-dichloropyrimidine through two routes in four steps and five steps, respectively. This method provided green and economical approaches toward numerous pyrrolo[2,3-<i>d</i>]pyrimidine derivatives.