Synthesis and crystal structures of three Schiff bases derived from 3-formylacetylacetone and benzyl-, tert-butyl- and (S)-methylbenzylamine

Abstract

Treatment of 3-formylacetylacetone with the amines benzylamine, tert-butylamine and (S)-methylbenzylamine led to the formation of the corresponding Schiff bases 3-[(benzylamino)methylidene]pentane-2,4-dione, C13H15NO2 (1), 3-[(tert-butylamino)methylidene]pentan-2,4-dione, C10H17NO2 (2) and 3-{[(S)-benzyl(methyl)amino]methylidene}pentane-2,4-dione, C14H17NO2 (3). The molecules of all three compounds exist as enamine tautomers that contain a nearly planar amino-methylene-pentane-2,4-dione core with a strong intramolecular N—H...O hydrogen bridge. The R group attached to the enamine N atom has no significant influence on the bond lengths and angles of the amino-methylene-pentane-2,4-dione core. The supramolecular structures in 1–3 are mainly based on weak C—H...O hydrogen bonds.

Keywords

• crystal structure
• enamine
• 3-formylacetylacetone
• schiff base