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A Water-Soluble Ruthenium Glycosylated Porphyrin Catalyst for Carbenoid Transfer Reactions in Aqueous Media with Applications in Bioconjugation Reactions

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journal contribution
posted on 17.02.2010 by Chi-Ming Ho, Jun-Long Zhang, Cong-Ying Zhou, On-Yee Chan, Jessie Jing Yan, Fu-Yi Zhang, Jie-Sheng Huang, Chi-Ming Che
Water-soluble [RuII(4-Glc-TPP)(CO)] (1, 4-Glc-TPP = meso-tetrakis(4-(β-d-glucosyl)phenyl)porphyrinato dianion) is an active catalyst for the following carbenoid transfer reactions in aqueous media with good selectivities and up to 100% conversions: intermolecular cyclopropanation of styrenes (up to 76% yield), intramolecular cyclopropanation of an allylic diazoacetate (68% yield), intramolecular ammonium/sulfonium ylide formation/[2,3]-sigmatroptic rearrangement reactions (up to 91% yield), and intermolecular carbenoid insertion into N−H bonds of primary arylamines (up to 83% yield). This ruthenium glycosylated porphyrin complex can selectively catalyze alkylation of the N-terminus of peptides (8 examples) and mediate N-terminal modification of proteins (four examples) using a fluorescent-tethered diazo compound (15). A fluorescent group was conjugated to ubiquitin via 1-catalyzed alkene cyclopropanation with 15 in aqueous solution in two steps: (1) incorporation of an alkenic group by the reaction of N-hydroxysuccinimide ester 19 with ubiquitin and (2) cyclopropanation of the alkene-tethered Lys6 ubiquitin (23) with the fluorescent-labeled diazoacetate 15 in the presence of a catalytic amount of 1. The corresponding cyclopropanation product (24) was obtained with 55% conversion based on MALDI-TOF mass spectrometry. The products 23, 24, and the N-terminal modified peptides and proteins were characterized by LC-MS/MS and/or SDS-PAGE analyses.