A one-pot synthesis of 1,6,9,13-tetraoxadispiro(4.2.4.2)tetradecane by hydrodeoxygenation of xylose using a palladium catalyst

• Pentoses are converted to 1,6,9,13-tetraoxadispiro(4.2.4.2)tetradecane in a single reactor.
• The crystalline product undergoes a phase change from triclinic to monoclinic between 175 K and 220 K.
• The Pd on silica-alumina catalyst can be reused at least three times.
• The product can be ring-opened to 1,5-dihydroxy-2-pentanone.

In an effort to expand the number of biobased chemicals available from sugars, xylose has been converted to 1,6,9,13-tetraoxadispiro(4.2.4.2)tetradecane in a one-pot reaction using palladium supported on silica-alumina as the catalyst. The title compound is produced in 35–40% yield under 7 MPa H2 pressure at 733 K using 3–10 wt%Pd on silica-alumina catalyst. It is isolated using a combination of liquid-liquid extractions and flash chromatography. This dimer can be converted to its monomer, 2-hydroxy-(2-hydroxymethyl)tetrahydrofuran, which ring opens under acid conditions to 1,5-dihydroxy-2-pentanone. This diol can then be esterified with vinylacetate in phosphate buffer to produce 1,5-bis(acetyloxy)-2-pentanone which is an inhibitor of mammalian 11β-hydroxysteroid dehydrogenase 1. 1H and 13C nmr spectra of each of these species are reported. The single crystal X-ray structure of the title compound is also reported. These data were collected in a temperature range of 100 K–273 K and show a solid state phase change from triclinic to monoclinic between 175 K and 220 K without a conformational change.

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