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DOI: 10.1055/sos-SD-042-00920

McKenna, C. E.; Kashemirov, B. A.; Błażewska, K. M.Science of Synthesis, (200942812.

The selective hydrolysis of triesters of phosphoric acid is a very convenient method for the preparation of dialkyl or diaryl phosphates under mild conditions. This method can be used in the synthesis of oligonucleotides,[‌90‌] caged phosphoproteins,[‌91‌] phospholipids,[‌92‌,‌93‌] and many other types of phosphate diester. Implementation of this approach generally entails the selective removal of a susceptible esterifying group (such as a methyl, tert-butyl, or 2-cyanoethyl) group from the triester. The tert-butyl group can be easily removed by treatment with trifluoroacetic acid.[‌91‌] Triethylamine and butylamine are convenient nucleophiles for the demethylation of phosphoric acid triesters,[‌93‌] and a sterically hindered primary amine (tert-butylamine) is effective for the elimination of the 2-cyanoethyl group from oligonucleotide triester intermediates.[‌94‌] When two 2-cyanoethyl groups are present, as for example in phosphate triester 93, only one is normally removed by the amine base to give the product, e.g. 94 (Scheme 30).[‌92‌]

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