Reactions expanding the aziridine ring

Abstract

Azirine reacts with 2-vinylpyridine in the presence of metallic sodium with the formation of N-[fl -(pyridin-2-yl)e thyl]azirine. The reaction of the latter with HBr and H2S leads to N-bromoethyl)- and N-(/~ -mercaptoethyl)- N- [fl -(pyridin-2-yl)e thyl]amines. Carbon oxysulfide and carbon disulfide react at room temperature with N-~-(pyridin-2-y l)ethyl]azirine to form copolymers in a ratio of 1 : 1. Carbon dioxide forms only N-~ -(pyridin-2-yl)e thyl]oxazolinone under similar conditions. Azirine adds to styrene in the presence of metallic sodium [2,3]. We have observed the addition of azirine to 2-vinylpyridine under similar conditions with the formation of N-[fi-(pyridin-2 -yl)ethyl]azirin e (I). The three-membered ring of the azirine (I) is easily cleaved under the action of hydrobromic acid, giving the dihydrobromide of the amine (Ha}, which was also obtained by treating with hydrobromic acid the product of the ethoxylation of N-[fl-(pyridin-2 -yl)ethyl]amine. The reaction of the azirine (1) with hydrogen sulfide formed the aminoethyl mercaptan (IIb), which was also prepared by the alkaline treatment of the dihydrobromide of N-{fl -[fl -(pyridin-2-yl)e thylamino]ethyl} isothiouronium bromide. Under the action of catalytic amounts of hydrohalic acids, (I) polymerizes, giving a water-soluble low polymer. The reaction of the azirine (D with carbon dioxide, carbon oxysulfide, and carbon disulfide, unlike that of the N-arylazirines, takes place without a catalyst. Carbon oxysulfide and carbon disulfide react very vigorously at room temperature, giving the peculiar copolymers (III).