Synthesis of Enantioenriched Indole-Fused Rings through Asymmetric (4+3) Cycloadditions of Indolyldimethanols with 5-Aminopyrazoles

We developed an efficient and operationally simple chiral phosphoric acid-catalyzed method for the straightforward synthesis of enantioenriched indole-fused azepane derivatives via the reaction of indolyldimethanols with 5-aminopyrazoles. A wide variety of enantioenriched indole-fused ring products were obtained in good yields with excellent enantioselectivities under mild conditions. In addition, a scale-up experiment and the synthetic transformations of the cycloadducts further highlighted their synthetic utility.