Abstract
Cycloaddition of a (-)-menthone-derived nitrone to racemic but-3-en-2-ol led to two spirobicyclic heterocycles, with opposite configurations at the C atom attached to the OH group. This paper describes the R epimer of the 1-hydroxyethyl substituent in imidazoisoxazole C17H30N2O3, (I). The S epimer, (II), is presented in the next article [Aouadi, Jeanneau & Praly (2007), Acta Cryst. E67, o1327-o1329]. The absolute configurations of both epimers were assigned from the known configuration of the starting (-)-menthone derived nitrone. In (I), there is an O-H (.) (.) (.) O hydrogen bond (O-H (.) (.) (.) O = 1.96 angstrom and O-H (. . .) O = 168 degrees) that links the molecules into left-handed helices along the b axis. In addition, there are C-H (. . .) O and C-H (. . .) N hydrogen bonds.