title: Combinatorial discovery of two-photon photoremovable protecting groups.
abstract: A design principle for a two-photon photochemically removable protecting group based on sequential one-photon processes has been established. The expected performance of such groups in spatially directed photoactivation/photodeprotection has been shown by a kinetic analysis. One particular molecular class fitting into this design, the nitrobenzyl ethers of o-hydroxycinnamates, has been presented. An initial demonstration of two-photon deprotection of one such group prompted further optimization with respect to photochemical deprotection rate. This was accomplished by the preparation and screening of a 135-member indexed combinatorial library. Optimum performance for lambda >350 nm deprotection in organic solvent was found with 4,5-dialkoxy and -cyano substitution in the nitrobenzyl group and 4-methoxy substitution in the cinnamate.
authors.affiliation: Department of Chemistry, Levine Science Research Center, Duke University, Durham, NC 27708-0317, USA. michael.pirrung@duke.edu
authors.forename: Michael C
authors.initials: MC
authors.lastname: Pirrung
authors.forename: Wolfgang H
authors.initials: WH
authors.lastname: Pieper
authors.forename: Krishna P
authors.initials: KP
authors.lastname: Kaliappan
authors.forename: Mugunthu R
authors.initials: MR
authors.lastname: Dhananjeyan
mesh_terms: D002934:Cinnamates / Q000737:chemistry / Q000528:radiation effects; D020650:Combinatorial Chemistry Techniques / Q000379:methods*; D007700:Kinetics; D008027:Light; D008958:Models, Molecular; D009578:Nitrobenzenes / Q000737:chemistry / Q000528:radiation effects*; D010777:Photochemistry / Q000379:methods*; D017785:Photons
chemical_list: D002934:Cinnamates; D009578:Nitrobenzenes