Polar crystal of vanillylformamide through replacement of the alkene by an isosteric formamide group

Abstract

Vanillylformamide [systematic name: N-(4-hydroxy-3-methoxybenzyl)formamide], C9H11NO3, (II), has been synthesized from vanillylamine hydrochloride and studied by single-crystal X-ray diffraction. Compound (II) and the well known biologically active eugenol compound (I) can be considered to be `isosteres' of each other, since they share comparable molecular shape and volume. The product (II) crystallizes in the space group P1. In the crystal, the vanillylformamide molecules are linked mainly by N—H...O, O—H...O and Csp2—H...O hydrogen bonds, forming infinite two-dimensional polar sheets. These two-dimensional layers pack in a parallel fashion, constructing a polar three-dimensional network. Except for van der Waals forces and weak Csp3—H...O hydrogen bonds, there are no significant intermolecular interactions between the layers. A Cambridge Structural Database search revealed that vanillylamide-related crystals are scarce.

Keywords

• polar crystal structure
• vanillylamine
• eugenol
• capsaicin analogs
• isosteres