1-(2-Cyclohex-2-enylpropionyl)-3-methylurea, 2-ethyl-5-methylhexanamide and 2-ethylpentanamide: three products of barbiturate decomposition.

The three title compounds were obtained by reactions which mimic, with more extreme conditions, the in vivo metabolism of barbiturates. 1-(2-Cyclohex-2-enylpropionyl)-3-methylurea, C(11)H(18)N(2)O(2), (I), and 2-ethylpentanamide, C(8)H(17)NO, (III), both crystallize with two unique molecules in the asymmetric unit; in the case of (III), one unique molecule exhibits whole-molecule disorder. 2-Ethyl-5-methylhexanamide, C(9)H(19)NO, (II), crystallizes as a fully ordered molecule with Z' = 1. In the crystal structures, three different hydrogen-bonding motifs are observed: in (I) a combination of R(2)(2)(4) and R(2)(2)(8) motifs, and in (II) and (III) a combination of R(4)(2)(8) and R(2)(2)(8) motifs. In all three structures, one-dimensional ribbons are formed by N-H···O hydrogen-bonding interactions.