Alcohols photoremovable protecting

Literak, J., Wirz, J. and Klan, P. (2005) 2,5-Dimethylphenacyl carbonates A photoremovable protecting group for alcohols and phenols. Photochemical el... 

Pirrung, M.C. and Shuey, S.W. (1994) Photoremovable protecting groups for phosphorylation of chiral alcohols. Asymmetric synthesis of phosphotriesters of (—)-3, 5 -dimethoxybenzoin. Journal of Organic Chemistry, 59, 3890-3897. 

The use of an N-aryImethyl substituent as a photoremovable protecting group for adenines has been proposed thus N-aryImethyl adenines such as (413) are converted in quantitative yield to the parent adenine and the benzyl alcohol upon photolysis in water. 

Photoenolization [45], one of the well-documented [46] photochemical rearrangements of o-alkylphenacyl groups (Scheme 17.15) can be used for the deprotection of alcohols [47], carboxylic acids [48] and phosphates [49]. Klan chose the 2,5-dimethylphenacyl (DMP) chromophore [30] as a photoremovable protecting group, and its photolysis with >280 nm UV radiation results in an almost quantitative yield of deprotection. 

A recent example of the use of 2,2-dimethoxypropane in the above capacity involves the reaction of an aldehyde or ketone with o-Nitrobenzyl Alcohol to afford the bis-o-nitrobenzyl acetal derivative. This protecting group has the advantage that it is photoremovable in high yield by irradiation at 350 nm. 

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