The synthesis of a new class of lawsone enaminone derivatives by using lawsone, triethyl orthoformate and aromatic amines in the presence of guanidinium chloride under solvent-free conditions has been developed. Investigation of 1H-NMR spectra indicated that lawsone enaminones exist in the ketoenamine tautomeric form and undergo Z/E-isomerization with respect to the C
C bond in DMSO-d6 at room temperature. Furthermore, intramolecular hydrogen bonds have been observed in the synthesized compounds. This method has some advantages including short reaction times, high to excellent yields, simple work-up procedure and very easy purification of products by non-chromatographic methods.
![Graphical abstract: Green synthesis of new lawsone enaminones and their Z/E(C [[double bond, length as m-dash]] C)-isomerization induced by organic solvent](http://hg.y866.cn/compound/lib/scimg/usr/1/D1RA01858B.jpg)