New Protocol for Efficient N-Chlorinations of Amides and Carbamates [1]

Abstract

N-Chlorination of various amides, carbamates and lactams with inexpensive and stable calcium hypochlorite on moist alumina proceeds smoothly and efficiently, e.g. the technically important 1-chlorohexahydroazepin-2-one (3-Cl) and 1-chloropyrrolidin-2-one (7-Cl) were obtained in 95% and 98% yield, respectively. Excellent results were also observed for the N-chlorination of protected amino acid esters with a cyclopropane moiety to give derivatives such as methyl (tert-butoxycarbonylchloroamino)cyclopropylacetate (1-Cl), methyl (benzyloxycarbonylchloroamino)cyclopropylacetate (2-Cl), methyl 1-(tert-butoxycarbonylchloroamino)cyclopropanecarboxylate (5-Cl) and methyl trans-2-(tert-butoxycarbonylchloroamino)cyclopropanecarboxylate (6-Cl) in 99%, 96%, 90% and 97% yield, respectively.

Key words

amides - amino acids - N-chlorination - calcium hypochlorite - alumina

References

• 1a

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• (c) See ref. 23a,c.

13

Larionov, O. V.; de Meijere, A. manuscript in preparation.

14

N-chlorination of the cyclopropyl-containing amino acid derivatives 1-H and 2-H with any of the other known reagents was to a greater extent hampered by some side-processes furnishing the products 1-Cl and 2-Cl respectively in low yields and purities.

16

Larionov, O. V. Part of a forthcoming Dissertation, University of Göttingen 2004.