A Protection-Deprotection Method for the Synthesis of Substituted Benzoyloxybenzoates

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Abstract
Common syntheses of phenyl benzoyloxybenzoates generally produce products in low yields. A variety of synthetic pathways were employed in an attempt to increase the overall yield of the final product. It was found that catalytic agents such as boron trifluoride-etherate (BF3 Et2O), 1,3-dicyclohexylcarbodiimide (DCC), and 4-N, N-di-methylaminopyridine (DMAP) were relatively ineffective in these processes. However. protection of the hydroxy moiety of an appropriately substituted benzoic acid with methyl chloroformate, followed by esterification under normal conditions, and deprotection with ammonia in ethanol produces the hydroxy-benzoyloxybenzoate intermediate. This material can be used in further esterifications to produce phenyl benzoyloxybenzoate compounds in good yield. Materials such as the triply reentrant compound 4-n-nonyloxyphenyl 4-nitrobenzoyloxybenzoate (DB9ONO2) can be prepared by this method.