Vibrational spectroscopic studies, theoretical aspects, and X-ray analysis of xanthenodiones (1,8-dioxooctahydroxanthenes)

Abstract

Compounds containing a pyran moiety fused to two cyclohexen-2-one rings are collectively called xanthenodiones (1,8-dioxooctahydroxanthenes). With the aim of increasing the knowledge about the structures of xanthenodiones, in the present investigation two xanthenodiones, namely 9-(4-hydroxy-3-methoxyphenyl)-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione (1) and 9-(4-hydroxyphenyl)-3,6-diisopropyl 3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione (2), were synthesized. Their structures were investigated by nuclear magnetic resonance, single-crystal X-ray diffraction, infrared (IR), and Raman spectroscopy techniques along with mass spectrometry. In addition, a computational study was carried out involving vibrational spectroscopy, which allowed us to assign vibrational modes and their shifts as lattice environment. Even though compound 2 has two stereocenters, it crystallized in a centrosymmetric space group (P21/c) as expected from its achiral synthesis. This compound also crystallized as monohydrate and the presence of water molecule did not change the conformation of the target compounds.