O Nitrobenzyl group

Photolytic cleavage reactions (e.g., of o-nitrobenzyl, phenacyl, nitrophenylsul-fenyl derivatives) take place in high yield on irradiation of the protected compound for a few hours at 254-350 nm. For example, the o-nitrobenzyl group, used to protect alcohols, amines, and carboxylic acids,has been removed by irradiation. Protective groups that have been removed by photolysis are described at the appropriate places in this book in addition, the reader may wish to consult five review articles. 

This approach offers unique opportunities for the generation of multi-functionalized cyclic 2-azadiene systems. A wide variation of the substitution pattern at the positions N-1 and C-6 can be determined by an appropriate choice of the aldehyde and amine. Various substituents can easily be introduced at the C-3 position via addition/elimination reactions on the sensitive imidoyl chloride moiety [24]. Upon reaction with bi-functional reagent, an adequately AT-protected 2(lH)-pyrazinone was elaborated into C-nucleoside analogues (Scheme 8). The desired skeleton and functionalities were obtained by oxidation-cyclization reaction followed by photochemical removal of the protective o-nitrobenzyl group [25]. 

Many other linkers besides those listed above have been developed for two-phase synthesis of oligosaccharides on insoluble supports, and it can be expected that at least some of them will be tested on soluble supports. It should be kept in mind that MPEG-supported syntheses can be easily scaled up therefore, any relationship between both types of polymer supports will be cooperative rather than mutually exclusive. Such linkers will most probably include dialkyl- or diaryl-silyl linkers,10,41 3 and linkers cleavable by photolysis such as the o-nitrobenzyl group and its modifications.44 16... 

The substitutions by o-nitrobenzyl groups are used for dioxolane and 1,3-dioxane derivatives, but the photochemical cleavage is only partially regioselective. However,... 

The o-nitrobenzyl group was also used in nucleotide synthesis with the preparation of 2-0-(o-nitrobenzyl) rihonucleoside for oligon honucleotide synthesis (Scheme 51) [104-106]. 

Hydrolysis of alkyl-substituted phosphine oxides is generally difficult, heating with solid sodium or potassium hydroxide is needed in order to break the P—C bond. Hydrolysis of phosphonates and phos-phinates occurs with P—O cleavage in preference to P—C cleavage. Exceptions have been reported with several aromatic phosphine oxides containing p- and o-nitrobenzyl groups and other stabilized systems. Perfluorinated phosphine oxides can also be hydrolyzed to the phosphinic and phosphonic acids.2 ... 

In 1962, Barltrop et al. reported the release of glycine from its nitrobenzyl carbamate upon photolysis [8]. Today, the o-nitrobenzyl group and its... 

Preparation of caged proteins by introduction of an o-nitrobenzyl group directed toward specific residues dates back to the mid-1990s. In a pilot study, bovine serum albumin (BSA) was randomly labeled with up to 15... 

Ring-substituted derivatives of the o-nitrobenzyl group were used to modify enzymes and other proteins selected to serve as models for this method. The modified proteins were irradiated with filtered light at wavelengths (350-400 nm) known not to cause photo-damage to proteins. 

Polystyrene, incorporating /7-hydroxyphenyl groups Polystyrene, incorporating o-nitrobenzyl groups Poly(ethylene glycol) H(0CH2CH2) -0H MW = 2,000-20,000 (soluble) Copolymer of... 

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