Carbanion-Mediated Photocages:Rapid and Efficient Photorelease with Aqueous Compatibility

摘要

Photoremovable protecting groups or "photocages" provide biochemists with powerful tools for the rapid introduction of a variety of compounds to biological systems with spatial and temporal control,allowing the time-resolved study of the ensuing events.They have found use in other fields ranging from molecular array (biochip) synthesis to time-resolved X-ray crystallography.The most widely used photocage,the o-nitrobenzyl (oNB) group,suffers from major disadvantages,specifically,slow release rate following excitation (typically several microseconds or longer),poor aqueous solubility,and formation of reactive nitrosoaldehyde byproducts.Much effort has been devoted to the development of new photocages that overcome one or more of the drawbacks associated with the oNB group,although no candidate has emerged with a sufficiently desirable combination of properties to challenge its dominance.We report the development of a new photocage that is superior to the oNB group in several respects,including a release rate improvement of over 1000-fold,a higher photorelease quantum yield,excellent aqueous solubility,and formation of benign photoproducts.This photocage is capable of releasing a wide variety of biologically relevant substrates,including alcohols and carboxylic acids.