Cascade sulfa-Michael/aldol reaction of (het)arylmethylidenefuran-2(3H)-ones with 1,4-dithiane-2,5-diol

Introduction

At the moment, the chemistry of heterocyclic compounds is actively developing. Particularly attractive are spirocyclic heterocompounds, which are of great interest from a synthetic point of view in chemical science due to their predominance in a wide range of pharmacologically important compounds. In particular, sulfur-containing hybrid heterocycles are the structural units of many biologically active natural compounds.

Experimental details

We have developed the conditions and studied the interaction of (E)-3-[(2-oxo-5-arylfuran-3(2H)-ylidene)methyl]-4H-chromen-4-ones with 1,4-dithiane-2,5-diol at room temperature using acetonitrile as a solvent. The final products of the transformation are 3-(3-aryl-9-hydroxy-1-oxo-2-oxa-7-thiaspiro[4.4]non-3-en-6-yl)-4H-chromen-4-ones. The composition and structure of sulfur-containing hybrid heterocycles were established on the basis of complex data from elemental analysis, IR, ¹H, ¹³C NMR, HSQC, HMBC spectroscopy.

Results and Discussion

The reaction under study is a cascade reaction and occurs in two stages. Initially, there is a thio-Michael addition of 2-mercaptoacetaldehyde (generated in situ from 1,4-dithiane-2,5-diol) to (E)-3-[(2-oxo-5-arylfuran-3(2H)-ylidene)methyl]-4H-chromen-4-ones. Then, intramolecular condensation occurs, which leads to the construction of a five-membered tetrahydrothiophene framework and the formation of the final hybrid compounds - 3-(3-aryl-9-hydroxy-1-oxo-2-oxa-7-thiaspiro[4.4]non-3-en-6-yl)-4H-chromen-4-ones.