Gold-Catalyzed Cyclization of Nonterminal Propargylic Amides to Substituted Alkylideneoxazolines and -oxazines
作者:A. Stephen K. Hashmi、Andreas M. Schuster、Martin Schmuck、Frank Rominger
DOI:10.1002/ejoc.201100342
日期:2011.8
The substrate scope of the gold-catalyzedcyclization of nonterminal propargylic amides to oxazolines and oxazines was investigated. Sixteen alkyl-substituted and 35 aryl-substited substrates were prepared by a very variable route from trimethylsilyl-(TMS-)protected, nonterminal propargylamines. Steric and electronic influences of the substituents on product selectivity were studied. A chloromethyl
A transition metal-free method for the cycloisomerization of propargylicamides to oxazoles was developed. The reaction utilizes in situ generated hydrogen chloride in hexafluoroisopropanol (HFIP). With the aid of Design of Experiments optimization a wide range of substrates was transformed into the desired oxazoles. The method allows product formation without side reactions eliminating the need for