Cesium carbonate → tert-Butyl 4-(5-(thiophen-2-yl)tetrazolo[1,5-a]pyrazin-8-yl)piperazine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

A 1 L round bottom flask was charged with tert-butyl 4-(5-bromotetrazolo[1,5-a]pyrazin-8-yl)piperazine-1-carboxylate (50 g, 0.13 mol), thiophene-2-boronic acid (22 g, 0.17 mol), tetrakis(triphenylphosphine)palladium(0) (7.5 g, 6.5 mmol), Cs2CO3 (51 g, 0.16 mol), 1,4-dioxane (600 mL) and H2O (240 mL). After the air was purged by bubbling N2 into the solution, the resulting solution was stirred at 80° C. under N2 for 10 h. Work-up: the reaction mixture was concentrated in vacuo. The residue was purified by flash column chromatography on silica gel eluted with CH2Cl2, and then crystallized from methanol, to afford 35 g (70%) of the product as a yellow solid. MS m/z: 388 (M+H+).

Provenance & Evidence