Direct regioselective 2-O-(p-toluenesulfonylation) of sucrose
作者:Katsunori Teranishi
DOI:10.1016/s0008-6215(02)00039-3
日期:2002.4
2-O-(p-Toluenesulfonyl)sucrose was regioselectively synthesized by direct p-toluenesulfonylation of sucrose using N-(p-toluenesulfonyl)imidazole in the presence of molecular sieves at 40degreesC. The reactivities of the sucrose hydroxy groups toward this sulfonylation increased in the order as follows: OH-2 much greater than OH-1' > OH-3' > OH-6 > OH-6'. These results were diametrically opposite to the expected sulfonylation with p-toluenesulfonyl chloride in pyridine. for which the reactivity increased in the order as follows: OH-6', OH-6 much greater than OH-1' > OH-2. The desired 2-O-(p-toluenesulfonyl)sucrose was readily isolated by simple open reversed-phase column chromatography. followed by recrystallization, thus overcoming the main difficulties associated with regioselectivity, efficiency, and isolation techniques for the practical preparation. (C) 2002 Elsevier Science Ltd. All rights reserved.
Library of mild and economic protocols for the selective derivatization of sucrose under microwave irradiation
作者:M. Teresa Barros、Krasimira T. Petrova、Paula Correia-da-Silva、Taterao M. Potewar
DOI:10.1039/c1gc15228a
日期:——
The chemistry of sucrose is very challenging due to its eight hydroxyl groups, three of which are primary, with very similar reactivities, thus control of the chemoselectivity is a central issue. In this work, the selective formation of monounsaturated esters at the 6-position, by applying the Mitsunobu conditions for the selective esterification of sucrose, is reported. Also, the outcome of a number of mono-substitution reactions at positions 6 or 6′, and di-substitution reactions at positions 6 and 6′ have been explored. Mild and energy-efficient procedures, with short reaction times (5 to 10 min) using microwave irradiation have been developed, and the results compared with conventional procedures. In some cases, the use of microwave irradiation appeared to provide not only time saving but also improved selectivity.