Photolabile protecting group for histidine

Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy

“…The leaving group can be directly attached to the benzylic site, as in 57 , and this is the typical mode for the release of carboxylic acids, 3 thiols, 174 histidine, 175 and phosphates (Scheme 34, several examples shown). 5,107b Although it is possible to directly attach alcohols and amines, they are most frequently linked as carbonic acid derivatives 58 (X = OCO–X′), which are better leaving groups and make the synthesis more convenient, i.e., by the direct reaction of the alcohol or amine with the readily available o -nitrobenzyl chloroformate.…”

Photolabile protecting groups and linkers

“…The o-nitrobenzyl group was also used for the direct protection of the imidazole side-chain of histidine, by N-alkylation with the corresponding bromide (Scheme 3). 18 The photolysis (medium-pressure Hg-lamp with pyrex filter) liberated back quantitative yields of histidine, and no racemisation was detected.…”

Synthesis of an o-Nitrobenzyl Attached A1 Adenosine Receptor Antagonist, a Prodrug Approach

“…193. 1,2S)-norbornan-2yl]xanthine (4). To the solution of (À)(1S,2S)-5-norborbene-2carboxylic acid [10] (5 g, 36 mmol) in CH 2 Cl 2 (125 mL), was added dropwise diluted oxalyl chloride (5 mL in 125 mL CH 2 Cl 2 ).…”

“…[3] The o-Nitrobenzyl group, a special nitrogen protective group that is stable under most of conditions, can be cleaved by irradiation at 320 nm for 1 h in nearly quantitative yield. [4] This protective group has been used widely in a variety of structure syntheses. [5] It is important to mention that besides traditional photolytic conditions, removal of the o-nitrobenzyl group could also be carried out efficiently using direct sunlight.…”