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37.8.6.2.3 Method 3: Reaction with Carbon Tetrabromide under Reflux

DOI: 10.1055/sos-SD-037-00601

Petursson, S.Science of Synthesis, (200837889.

The importance of the ease of operation and compatibility with other functional groups during deprotection has already been stressed. With this in mind, it is fitting to end this discussion of the trityl and methoxytrityl protecting groups with a method for their removal published in 2000. The method uses carbon tetrabromide in refluxing methanol with reaction times from 1.5 to 5hours.[‌142‌] This is illustrated in Scheme 48 with the detritylation of 3-O-allyl-5-O-trityl-1,2-O-isopropylidene-α-d-xylofuranose (82), which gives 92% yield of the detritylated product 83. All the other examples given, mainly based on 1,2-O-isopropylidene-α-d-xylofuranose with the trityl or dimethoxytrityl in the 5-O position and the other protecting group in the 3-O position, give yields of around 90%. The functional groups tested for compatibility with the method are, in addition to the two already mentioned, O-benzyl, O-benzoyl, O-methyl, O-acetyl, O-tosyl, O-4-methoxybenzyl, O-methylbut-2-enyl (prenyl), O-tert-butyldiphenylsilyl, N-tert-butoxycarbonyl, N-carboxybenzyl, and a double bond.

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