Find in Library

An environment-friendly photochemical approach to the synthesis of 4a,7a-dihydroxy-1-(2-hydroxyethyl)-5-methyl-2′,3′,4a,5′,6′,7a-hexahydrospiro[cyclopenta[<i>b</i>]pyridine-4,4′-pyran]-2,7(1<i>H</i>,3<i>H</i>)-dione from 2-(4-(3-hydroxy-6-methyl-4-oxo-4<i>H</i>-pyran-2-yl)tetrahydro-2<i>H</i>-pyran-4-yl)-<i>N</i>-(2-hydroxyethyl)acetamide was elaborated. The suggested method is based on the ESIPT-promoted contraction of 3-hydroxypyran-4-one fragment followed by intramolecular cyclization of generated in situ α-hydroxy-1,2-diketone intermediate. The distinctive feature of the presented protocol is the employment of water as a solvent for the considered photoreaction. The structure of the obtained photoproduct was confirmed by ¹H, ¹³C-NMR, IR spectroscopy and high-resolution mass spectrometry.