Introduction

Compounds containing a dimethylaminomethylidene moiety are widely used as platform compounds in the design and creation of new heterocyclic systems possessing both high reactivity and a wide spectrum of biological activity. The presence of several reaction centers, as well as a well-leaving dimethylamino group, determines the synthetic potential of dimethylaminomethylidene derivatives of furan-2(3H)-thiones in transamination reactions involving N-nucleophilic reagents.

Experimental details

The synthesis of 3-[((2-aminophenyl)amino)methylidene]-5-arylfuran-2(3H)-thiones was carried out by the reaction of 3-[(dimethylamino)methylidene]-5-arylfuran-2(3H)-thiones with 1,2 -phenylenediamine in an equimolar ratio when boiling in isopropyl alcohol. Based on IR and NMR spectroscopy data, the structure of the resulting products was established.

Results and Discussion

The synthetic potential of 3-[(dimethylamino)methylidene]-5-arylfuran-2(3H)-thiones in transamination reactions involving an aromatic amine containing an electron-donating substituent, 1,2-phenylenediamine, was studied for the first time. Boiling the reaction mixture in isopropyl alcohol in the absence of a catalyst was chosen as optimal conditions, which made it possible to isolate the final products in high yields. A probable scheme for the occurrence of this interaction is proposed. Using IR spectroscopy, it was found that the final products were isolated in the aminomethylidene tautomeric form. Based on NMR spectroscopy data using a two-dimensional NOESY 2D experiment, it was established that the synthesized 3-[((2-aminophenyl)amino)methylidene]-5-arylfuran-2(3H)-thiones exist in the cis-enamine configuration.