2-(2-Cyclobutylideneethyl)-3,5,6-trimethylbenzo-1,4-quinone → 5,7,8-Trimethylspiro[chromene-2,1'-cyclobutan]-6-ol

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Reaction Steps

The above 2-(2-cyclobutylideneethyl)-3,5,6-trimethylbenzo-1,4-quinone was dissolved in pyridine and the mixture was heated to reflux for 15 h. The solvent was removed under reduced pressure and the residue was chromatographed to afford 5,7,8-trimethylspiro[chromene-2,1′-cyclobutan]-6-ol (420 mg). 1H-NMR (300. MHz, CDCl3) δ=6.59 (d, J=9.9 Hz, 1H), 6.07 (d, J=9.9 Hz, 1H), 4.39 (s, 1H), 2.47 (m, 2H), 2.26-2.17 (m, 11H), 1.90 (m, 1H), 1.75 (m, 1H) ppm. 13C-NMR (75 MHz, CDCl3) δ=145.6, 144.6, 128.9, 123.0, 122.3, 120.2, 118.5, 116.2, 37.0, 12.5, 12.3, 11.8, 11.0 ppm. MS m/z: 231 (M+H+).

Provenance & Evidence