The title compounds consist of a bornane skeleton with attached acetamide, C12H21NO (±)-(1) {systematic name: (±)-N-[(1RS,2RS,4RS)-1,7,7-tri-methylbi-cyclo-[2.2.1]heptan-2-yl]acetamide}, and chloro-acetamide, C12H20ClNO (±)-(2) {systematic name: (±)-2-chloro-N-[(1RS,2RS,4RS)-1,7,7-tri-methylbi-cyclo-[2.2.1]heptan-2-yl]-acetamide}, functionalities to the 2-exo-position. The crystal structure of the first monoclinic polymorph of (±)-(1) has been reported previously [Ung et al. (2014 ▸). Monatsh. Chem. 145, 983-992]. Compound (±)-(1) crystallizes in the space group P21/n with two independent mol-ecules in the asymmetric unit, in contrast to the above-mentioned polymorph which crystallized in the space group C2/c with one mol-ecule in the asymmetric unit. In the title compounds, the bicyclic bornane moieties have normal geometries. In the crystals of both compounds, mol-ecules are linked by N-H⋯O hydrogen bonds, reinforced by C-H⋯O contacts, forming trans-amide chains propagating along the a-axis direction. In the case of compound (±)-(1), neighbouring chains are linked by further C-H⋯O contacts, forming double-chain ribbons along [100].
Keywords: (±)-exo-N-isobornylacetamides; Ritter reaction; crystal structure; hydrogen bonding; polymorph.