The crystal structure of KR-21042, an analgesic capsaicinoid.

The crystal structure of KR-21042, N-(3-Phenylpropyl)-4-hydroxy-3-methoxyphenylacetamide, was determined by single crystal X-ray diffraction analysis. The compound was recrystallized from a mixture of ethylacetate and n-hexane in monoclinic, space group P21/c, with a = 16.622(1), b = 6.215(1), c = 15.802(1) A, P= 104.97(1), and Z = 4. The calculated density is 1.261 g/cm3. The structure was solved by the direct method and refined by full matrix least-squares procedure to the final R value of 0.068 for 2332 observed reflections.