Newly intramolecular α-amidoalkylation cyclisation: Use of theN-acyliminium ion with a sulfur atom as a nucleophile
摘要:
Pyrrolidino(or isoindolo)[1,3]benzothiazines 1a,b were efficiently synthesized in a four-step sequence from the known o-(benzylthio) benzyl alcohol 2. The key step was the nucleophilic attack of the sulfur atom onto N-acyliminium ion 6 which was generated in high acidic medium from omega-carbinol lactam 5. The last was regioselectively obtained by reduction of the parent imide 4. (C) 1994 Elsevier Science Ltd. All rights reserved.