Sodium Dithionite → 1-Methyl-3-[N-(2-{[1-(p-chlorobenzoyl)-5-methoxy-2-methyl-3-indolyl]acetoxy}ethyl)carbamoyl]-1,4-dihydropyridine

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Reaction Conditions

Reaction Steps

The indomethacin quaternary salt prepared in Example 95 (140 mg, 0.22 mmol), was dissolved in a minimum amount of water:acetonitrile (8:2). The water had been bubbled with nitrogen for 20 minutes prior to its use. Sodium bicarbonate (91 mg, 1.1 mmol) and sodium dithionite (110 mg, 0.65 mmol) were added to the solution while stirring at 0° C. The solution was then allowed to warm to room temperature. The reaction was continued for about 1 hour. Some of the product had precipitated during the reaction. This was dissolved in ethyl ether. The water layer was extracted several times with ether until no more yellow color transferred to the organic layer. The ether portions were combined and dried with magnesium sulfate, filtered and the ether was removed under reduced pressure. The resulting oil was dissolved in acetone and the solvent was removed (2×10 mL) under reduced pressure to form a dry foam. The final product weighed 92 mg. The yield was 82%; mp 60°-65° C. The product had the formula: ##STR126## as confirmed by UV, NMR and elemental analyses.

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