Methanol → Methyl Spiro(cyclopropane-1,12'(12'H)-dibenzo[d,g][1,3]dioxocin)-6'-carboxylate

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Reaction Steps

The crude spiro(cyclopropane-1,12'(12'H)-dibenzo[d,g][1,3]dioxocin)-6'-carboxylic acid from Example 3 was dissolved in 500 ml of methanol and 2.0 ml of sulfuric acid added. The mixture was heated at reflux and stirred for 3 hours. About half of the methanol was removed by evaporation under reduced pressure and the remaining solution was diluted with 1.5 l of ether. The solution obtained was extracted several times with water and then with brine and was then dried over magnesium sulfate, filtered, and concentrated by evaporation under reduced pressure to obtain the title compound in impure form. This was purified by filtration chromatography, eluting with a 9:1 mixture of hexane and ether to obtain the product as a pale yellow crystalline solid. This was recrystallized from methanol to obtain 9.55 g of the title compound as pale tan crystals melting at 123°-126° C. The proton and carbon NMR and infrared spectra were consistent with the assigned structure.

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