The synthesis and 1H nuclear magnetic resonance spectra of 3,6-dihydro-1,2-oxazines

Abstract

The synthesis of 40 derivatives of 3,6-dihydro-1,2-oxazine making use of the Diels–Alder reaction of 1-chloro-1-nitrosocyclohexane is described. Unambiguous assignment of the structures of the oxazines was possible by means of ¹H n.m.r. Spectra through decoupling experiments. The adducts from isoprene and 2-phenylbutadiene are mixtures of isomers, the major products having 5-methyl and 4-phenyl groups respectively. N-Alkylation of the primary Diels–Alder adducts to give N-alkyl-substituted derivatives (R = Me, Et, Prⁱ, Bz, CO₂Et) is also reported.