A Modular System for the Preparation of Diazirine-Labeled Mannose Derivatives Using Thiourea Bridging

Abstract

The protein FimH is a bacterial lectin, which is utilized by Escherichia coli to adhere to the glycocalyx of potential host cells. FimH has specificity for α-mannosyl residues, as revealed by biological as well as X-ray studies. To further investigate the molecular details of carbohydrate binding to FimH, photolabile mannose derivatives are important tools to covalently mark carbohydrate binding sites on FimH. Here, a modular approach for the synthesis of photolabile diazirine-labeled mannosides and mannosyl clusters is reported. The convergent synthesis utilizes thiourea bridging of the amino-functionalized diazirine 4 with NCS-functionalized carbohydrates.