Crystal structures of two (±)-exo-N-isobornylacetamides

Abstract

The title compounds consist of a bornane skeleton with attached acetamide, C12H21NO (±)-(1) {systematic name: (±)-N-[(1RS,2RS,4RS)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-yl]acetamide}, and chloroacetamide, C12H20ClNO (±)-(2) {systematic name: (±)-2-chloro-N-[(1RS,2RS,4RS)-1,7,7-trimethylbicyclo[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 molecules in the asymmetric unit, in contrast to the above-mentioned polymorph which crystallized in the space group C2/c with one molecule in the asymmetric unit. In the title compounds, the bicyclic bornane moieties have normal geometries. In the crystals of both compounds, molecules 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

• crystal structure
• Ritter reaction
• (±)-exo-N-isobornylacetamides
• polymorph
• hydrogen bonding