A Synthetic Route to Chiral Dihydrobenzothiazines through Ring Opening of Activated Aziridines with 2-Halothiophenols/Copper-Powder-Mediated C-N Cyclization

A simple protocol for the synthesis of dihydrobenzothiazines through regio- and stereoselective S(N)2-type ring opening of N-tosylaziridines with sulfur nucleophiles followed by copper-powder-mediated intramolecular C-N cyclization in excellent yields (up to 95%) with high diastereo- and enantioselectivity (up to >99%) is reported.