Silyl protecting groups, photochemically removable

Pirrung, M.C. and Lee, Y.R. (1993) Photochemically-removable silyl protecting groups. Journal of Organic Chemistry, 58, 6961—6963. 

Silyl protecting groups are the gold standard for the protection of alcohols.234 Novel photochemically removable protection groups for alcohols have been developed by Brook et a/.23S and Pirrung et al,236 For instance, cyclo-pentanol can be reacted with tris(trimethylsilyl)chlorosilane 53 in the presence of a mild base to yield the protected silyl ether 54. The protection group can be removed conveniently upon UV irradiation or by the use of Bu4NF (Scheme 12). 

The dimethyl phosphite esters (431) undergo a photochemically catalysed Arbuzov i.somerization to the phosphonates (432 n = 1-3). The silyl protecting groups may be removed with Ph P/CBr and the resultant (w-bromoalkyl)phosphonic esters made to react with an activated heterocyclic base, the example of adenine being illustrated... 

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