Nitrobenzyl protective group

Bley, F., Schaper, K. and Gorner, H. (2008) Photoprocesses of molecules with 2-nitrobenzyl protecting groups and caged organic adds. Photochemistry and Photobiology, 84, 162—171. 

Photocleavage of phenacyl derivatives was first reported by Sheehan and Umezawa in 1973.40 In contrast to the 2-nitrobenzyl protecting groups, choice of solvent is important because the solvent acts as a hydrogen donor. The cleavage takes place by a radical mechanism as shown in Scheme L21. Typical solvents include ethanol dioxane and benzene containing cumene as hydrogen donor. 

The 2-nitrobenzyl protecting group has been most often exploited for the protection of amines in the form of A-2-nitrobenzyl amines and 2-nitrobenzyl car-... 

Scheme 1 Typical Route for Photocleavage of 2-Nitrobenzyl Protecting Groups l...

Figure 15.4 Examples of caged compounds and other photoactivatable drugs, (a) and (b) on photolysis the o-nitrobenzyl protecting group detaches and releases ATP and cAMP, respectively (c) photosensitive chelator. The cis form of the molecule binds Zn2+ but the trans form does not (d) frequently used photosensitive calcium chelators. Nitr-2 (R = CH3), Nitr-5 (R = H) (e) ICYP-diazirine, a photoaffinity reagent that becomes covalently attached to p-adrenergic receptors upon photolysis.

Use of o-nitrobenzyl protecting group in mononucleotide synthesis. Removed by irradiation (x>305 nm) in aqueous -butanol. 

The rate of release of ATP was found to be dependent on the pH and the relative concentration of magnesium ion in solution. Pelliccioli and Wirz have shown that the rate-determining step is the decay of the hemiacetal (or hemiketal) intermediate between pH 4 and 8. In this region, the slow hydrolysis of the hemiacetal limits the mechanistic value of the o-nitrobenzyl protecting group to studies of relatively... 

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