Facile syntheses of 3-halo and mixed 3,5-dihalo analogues of N-acetyl-l-tyrosine via sulfonic acid-catalysed regioselective monohalogenation
摘要:
The combination of catalytic amounts of p-toluenesulfonic acid and 1 equiv of N-halosuccinimide afforded highly selective ring-halogenation of N-acetyl-L-tyrosine, furnishing either N-acetyl-3-halo-L-tyrosine analogues or mixed 3,5-dihalo derivatives in a one-pot reaction with excellent yields at room temperature. (C) 2008 Elsevier Ltd. All rights reserved.