15N-Labelled 3-(Dimethylamino)-2,2-dimethyl-2H-azirine for Mechanistic Studies of Reactios with NH-Acidic Heterocycles

Article abstract of DOI:10.1002/hlca.19880710304

The synthesis of 3-(dimethylamino)-2,2-dimethyl(1-15N)-2H-azirine (1^*) was accomplished via reaction of 1-chloro-N,N,2-trimethyl-1-propenylamine (9) and sodium (1-15N) azide (Scheme 3).The earlier reported reactions of 1 with saccharin (10, Scheme 4), phthalimide (12, Scheme 5), and 2H-1,3-benzoxazin-2,4(3H)-dione (16, Scheme 6) were repeated with 1^*, and the position of the 15N-label in the products was determined by 15N-NMR spectroscopy.Whereas the postulated reaction mechanismus for 10 and 12 were confirmed by those experiments, the mechanism for the reaction of 16 had to be revised.With respect to the position of 15N in the products 17 and 18, a new mechanism is formulated in Scheme 7.Treatment of 5,5-dimethyl-1,3-oxazolidine-2,4-dione (19) with 1^* led to 3,4-dihydro-2H-imidazol-2-on 20 in which only N(3) was labelled.The mechanism of a ring expansion and transannular ring contraction as shown in Scheme 8 is in agreement with this finding.