New protocol for efficient N-chlorinations of amides and carbamates

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.