Di-tert-butyl furo[2,3-c]pyridin-7-ylimidodicarbonate (25 g, 75.3 mmol) in dry THF (350 mL) was cooled to between −65° C. and −75° C. and LDA (1.8 M in THF/heptanes/ethylbenzene, 50 mL, 90 mmol) was added via syringe over a period of 10 min. The mixture was stirred for 1.5 h between −65° C. and −75° C. and then treated with hexachloroethane (71.2 g, 0.30 mol) in dry THF (150 mL) added via syringe over a 30 min period. The mixture was allowed to warm to RT over 16 h and was quenched by the addition of water (100 mL) and stirred for 10 min. The reaction was diluted with EtOAc, the phases were separated and the aqueous phase was extracted with EtOAc (2×100 mL). The combined organic extracts were washed with water, dried over Na2SO4, filtered and concentrated in vacuo. The crude product thus obtained was purified by flash chromatography using triethylamine coated silica gel eluting (EtOAc:hexane mixtures) to provide 18 g (65%) of di-tert-butyl (2-chlorofuro[2,3-c]pyridin-7-yl)imidodicarbonate and 5 g (18%) of di-tert-butyl (2,3-dichlorofuro[2,3-c]pyridin-7-yl)imidodicarbonate.
