Selenoamides as powerful scaffold to build imidazo[1,5-a]pyridines using a grinding protocol

We describe the synthetic application of a family of selenoamides [R–C(Se)NHCH2R’ (R = Fc, Aryl, Het, alkyl) tethered to N-heterocyclic motifs (R’ = 2-pyridyl and 2-thiazolyl) obtained from their corresponding Fischer ethoxy carbene complexes [R–C(Cr(CO)5)OEt] using a tandem procedure that involves an aminolysis/seleniurative demetallation. The selenoamides obtained are used as accessible building-block to easily obtain a two-ring fused system with a bridge-head nitrogen atom. This study reveals that CSe bond can be readily and speedily activated with iodine at room temperature, in grinding conditions, for obtaining a family of imidazo[1,5-a]pyridines in good to excellent yields in only 1 min of reaction time. This methodology was successfully extended to the synthesis of ferrocenyl imidazo[1,5-b]thiazole in excellent yield. [Display omitted] •Selenoamides as potent scaffold to give imidazo[1,5-a]pyridines in excellent yields.•CSe bond can be readily and speedily activated with I2/Py at room temperature.•A grinding procedure allows the synthesis of the target compounds in only 1 min.•A general method for the exclusive formation of imidazo[1,5-a]pyridines.