A new synthetic approach to the 3,4-dihydro-1H-[1,4]oxazino[4,3-a]indole system from ethyl 1H-indole-2-carboxylates and activated glycerol carbonate

Abstract

An efficient synthesis of a small library of potentially bioactive 3,4-dihydro-1H-[1,4]oxazino[4,3-a]indoles is described through the reaction of ethyl 1H-indole-2-carboxylates and activated glycerol carbonate. The reactivity of the C-10 position of the system was utilized to access 10-halogenated, formylated, and (hetero)arylated derivatives, while the 3-hydroxymethyl appendage was further converted into various 3-O-, 3-S-, or 3-N-derivatives. The structures of the synthesized compounds were elucidated using ¹H-, ¹³C-, and ¹⁵N-NMR, IR spectroscopy, high-resolution mass spectrometry, and X-ray crystallography analyses. The photophysical properties of the selected compounds were investigated using spectroscopic techniques, including UV-vis and fluorescence spectroscopy.