“…General procedure C was followed using 3-methoxy-3-methyl-4-oxa-7-thia-1,2-diazaspiro [4.4] 2-(1,4-Dioxaspiro [4.5]decan-8-yl)-1H-benzimidazole (5e). General procedure C was followed using 3-methoxy-3-methyl-4,9,12trioxa-1,2-diazadispiro[4.2.4 8 .2 5 ]tetradec-1-ene (51 mg, 0.2 mmol, 1.0 equiv), formaldehyde (0.15 mL, 37 wt % in H 2 O, 2 mmol, 10 equiv), and o-phenylenediamine (32 mg, 0.3 mmol, 1.5 equiv). The crude mixture was purified via flash column chromatography (10−40% EtOAc in petroleum ether) to give the titled product as a white solid (41 mg, 80%): 1 tert-Butyl 4-(1H-Benzimidazol-2-yl)piperidine-1-carboxylate (5f).…”