Sodium Hydroxide → 3-[2,6-bis(1,1-Dimethylethyl)-(4H-selenopyran-4-ylidene)methyl]-4-hydroxvcyclobut-3-ene-1,2-dione

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Reaction Steps

This Example illustrates the preparation, by the reaction D→E shown in FIG. 1, of the squaric acid derivative of Formula II in which Q1 is a 2,6-bis(1,1-dimethylethyl)-4-selenopyrylidene grouping and R1 is a hydrogen atom. 3-[[2,6-bis(1,1-dimethylethyl)-4H-selenopyran-4-ylidene]methyl]-2,4,4-trichlorocyclobut-2-en-1-one (23 g, 52.4 mmole, prepared in Examples 48 and 49 above), trifluoromethane sulfonic acid (80 mL) and water (3 mL) were heated at 105° C. for three hours under nitrogen in a vessel fitted with an outlet connected to a gas-washing bottle containing 10% aqueous sodium hydroxide solution. The resultant dark solution was cooled to room temperature and added slowly to an ice/water mixture with rapid agitation. The resultant red solid was collected by filtration, washed with water and air dried, causing. its color to change to an iridescent green. The crude product so obtained was purified by trituration with cyclohexane for three hours. The pure 3-[[2,6-bis(1,1-dimethylethyl)-4H-selenopyran-4-ylidene]methyl]-4-hydroxycyclobut-3-ene-1,2-dione was collected by filtration, washed with cyclohexane, and dried to afford a red material (18 g, 94% yield). The structure of this compound was confirmed by mass spectroscopy and by 1H and 13C NMR spectroscopy.

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