Deuterative cyclization of sulfanyl 1,6-diynes: complete and monodeuteration of functional groups on heterocycles

Regioselective H/D exchange reaction of functional groups on heterocycles proceeded via a transition metal-free reductive cyclization of sulfanyl 1,6-diynes using sodium borodeuteride/ethanol-D-1. Both alkoxide- and aryloxide-mediated cyclizations and amination-cyclization resulted in the deuteration of functional groups with high deuterium incorporation. Reductive cyclization using sodium borodeuteride/ethanol exclusively afforded the monodeuterated furans and pyrroles in good yields.