Fluorescence Assay and Screening of Epoxide Opening by Nucleophiles

✍ Scribed by Fabrizio Badalassi; Gérard Klein; Paolo Crotti; Jean-Louis Reymond

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 193 KB
• Volume: 2004
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.200400024

✦ Synopsis

Abstract

Terminal epoxides such as 1 react with nucleophiles (H~2~O, Cl^−^, Br^−^, N~3~^−^, and CN^−^) at the primary oxirane carbon atom to give mostly anti‐Markovnikov‐type regioisomers 5a−d. The opening products of epoxide (R)‐1 with chloride (5a), bromide (5b) and azide (5c) are oxidized by horse liver alcohol dehydrogenase and NAD^+^ to give the corresponding ketones 7a−c and, subsequently, umbelliferone 4 by β‐elimination, leading to a fluorescence increase at λ~em~ = 460 ± 20 nm (λ~ex~ = 360 ± 20 nm). The epoxide hydrolysis products give no signal. We used this enantio‐ and chemo‐selective fluorogenic assay for epoxide opening to search for catalytic antibodies for nucleophilic epoxide opening that were raised against 1,2‐azidoammonium hapten 8, as a mimic for epoxide opening by azide, and against chloromethyl phosphonate hapten 9, as a mimic for the transition state of chlorohydrin formation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)