Hydrochloric Acid → Ethyl 1,4-diazepane-1-carboxylate

Participants

Reaction Steps

Combine [1,4]diazepane (33.9 g, 340 mmol) and water (250 mL). Add methyl orange and adjust the pH using 3 M aqueous hydrochloric acid solution until the indicator turns red. Add dropwise, ethyl chloroformate (38 mL, 400 mmol) over about 2.5 hours while maintaining the pH using first aqueous sodium acetate and then aqueous sodium hydroxide solution. After the addition is complete adjust the pH to 8 using aqueous sodium hydroxide solution and extract three times with diethyl ether. Discard the organic extracts and saturate the aqueous layer with potassium carbonate. Extract three times with diethyl ether. Combined organic layers from the second extraction, dry the over Na2SO4, filter, and evaporate in vacuo to give a 1-ethoxycarbonyl[1,4]diazepane.

Provenance & Evidence