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

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 [Unget al.(2014).Monatsh. Chem.145, 983–992]. Compound (±)-(1) crystallizes in the space groupP2₁/nwith two independent molecules in the asymmetric unit, in contrast to the above-mentioned polymorph which crystallized in the space groupC2/cwith 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, formingtrans-amide chains propagating along thea-axis direction. In the case of compound (±)-(1), neighbouring chains are linked by further C—H...O contacts, forming double-chain ribbons along [100].