Water → 2-methyl-3-pivaloyloxymethyl-3,4,7,8-tetrahydro-6H-cyclopenta[g]-quinazolin-4,6-dione

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Reaction Steps

70% tert-Butyl hydroperoxide solution (111 ml, 0.81 mol) was added during 3 minutes to a stirred suspension of chromium (VI) oxide (0.59 g, 5.9 mmol) in dichloromethane (232 ml) in a flask fitted with a reflux condenser, whilst cooling the mixture in a bath of water at room temperature. 2-Methyl-3-pivaloyloxymethyl-3,4,7,8-tetrahydro-6H-cyclopenta[g]quinazolin-4-one (36.586 g, 0.116 mol), prepared as described in Example 1(5), was added in portions during 2 minutes and the mixture was stirred at ambient temperature for 16 hours. It was then cooled to 0° C. and 10% aqueous sodium metabisulphite solution (195 ml) was added at such a rate that the temperature did not exceed 10° C. The resulting mixture was allowed to warm to room temperature and stirred for 21/2 hours. It was then partitioned between ethyl acetate (400 ml) and half-saturated brine (300 ml). The aqueous layer was extracted with ethyl acetate (2×150 ml) and the combined organic solution was washed successively with saturated aqueous sodium hydrogen carbonate (300 ml), saturated brine (2×150 ml), saturated aqueous sodium hydrogen carbonate (150 ml) and saturated brine (150 ml), then dried (MgSO4), treated with charcoal powder and evaporated to dryness. A portion of ethyl acetate was added and evaporated and the residue was crystallised from hexane-ethyl acetate to give 2-methyl-3-pivaloyloxymethyl-3,4,7,8-tetrahydro-6H-cyclopenta[g]-quinazolin-4,6-dione (10.371 g, 27%), m.p. 203°-205° C.

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