Syntheses and crystal structures of two piperine derivatives.

The title compounds, 5-(2H-1,3-benzodioxol-5-yl)-N-cyclohexylpenta-2,4-dienamide, C18H21NO3 (I), and 5-(2H-1,3-benzodioxol-5-yl)-1-(pyrrolidin-1-yl)penta- 2,4-dien-1-one C16 H17NO3 (II), are derivatives of piperine, which is known as a pungent component of pepper. Their geometrical parameters are similar to those of the three polymorphs of piperine, which indicate conjugation of electrons over the length of the molecules. The extended structure of (I) features N--H…O amide hydrogen bonds, which generate C(4) [010] chains. The crystal of (II) features aromatic τ-τ stacking, as for two of three known piperine polymorphs. [ABSTRACT FROM AUTHOR]