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Trichloroisocyanuric acid (TCCA): an efficient green reagent

Trichloroisocyanuric acid (TCCA), an inexpensive, commercially available, and non-toxic reagent has been used for the activation of thioglycosides toward their hydrolysis to the corresponding hemiacetals in high to excellent yields. The methodology provides a mild reaction condition for dealing with compounds containing acid sensitive functional groups.
Trichloroisocyanuric acid (TCCA), a commercially available, inexpensive, and non-toxic reagent, used in various organic syntheses is known to be a chlorinating agent too. Very recently, we have successfully used TCCA in the glycosylation reaction using both armed and disarmed donors. Its low pKa (1.8) and high active chlorine content (91.5%) indicate it to be an efficient chloronium ion generator, and thus is expected to activate thioglycoside to react with good nucleophiles without the requirement of any other strong acids as co-activator. Our proposition was eventually proved, as a model thioglycoside was hydrolyzed in the presence of TCCA at ambient temperature. Avoiding the use of strong acid as co-activator could make this method more attractive for hydrolyzing thioglycosides owing to the survival of acid-labile protecting groups present in carbohydrate derivatives. As a part of our ongoing research to prepare hemiacetals for the synthesis of diverse materials, we are pleased to report herein, hydrolysis of thioglycosides activated by TCCA, and the results are summarized. To the best of our knowledge, this is the first report of thioglycoside hydrolysis by TCCA.
After the success of the initial reaction we turned our attention to the evaluation of the hydrolyzing capability of Trichloroisocyanuric acid (TCCA) on a series of thioglycoside derivatives. A variety of other thioglycosides bearing OAc, OBz, OBn, Nphth, acetal, etc. protecting groups reacted under the standard protocol to produce the corresponding hemiacetals in high to excellent yields. In no case, formation of trace of sugar-isocyanuric acid adduct could be detected. In summary Trichloroisocyanuric acid (TCCA) has been utilized as a commercially available, non-toxic, inexpensive, and green reagent for efficient hydrolysis of thioglycosides under mild condition. A variety of commonly used, acid labile protecting groups remain unaffected in the presence of this reagent.