Ethyl chloroformate → Ethyl 1,4-diazepane-1-carboxylate

To a solution of homopiperazine (50.0 g, 0.5 mol) in aqueous HCl adjusted to pH 4 using approximately 400 mL of 2N HCl was added ethyl chloroformate (50 mL, 0.53 mol) dropwise maintaining the pH at 4 by the addition of 25% aqueous NaOH. The reaction mixture was brought to pH 14 with 25% aqueous NaOH and extracted with 3×250 mL of Et2O. These extracts were discarded and the aqueous was brought to pH 10 with 2N HCl and Na2CO3. After extracting the aqueous with 3×150 mL of Et2O, these combined extracts were dried over Na2SO4, and stripped of all solvent under reduced pressure. The residue was vacuum distilled at 0.1 mm of Hg and the title compound was obtained as the fraction (25.0 g) distilling at 103° C.

1. temperaturedropwise maintaining the pH at 4
2. extractionextracted with 3×250 mL of Et2O
3. extractionAfter extracting the aqueous with 3×150 mL of Et2O
4. dry with materialthese combined extracts were dried over Na2SO4
5. distillationdistilled at 0.1 mm of Hg

ORD record

ord-87e424634db742b4b052f779c1a5ed87

Source dataset

uspto-grants-1994_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05354747