Heteroannulation through copper catalysis: a novel cyclization leading to a highly regio- and stereoselective synthesis of 2-substituted benzothiazolines

3-(2-Aminophenylthio)prop-1-yne 8 reacted with aryl iodides 9−18 under palladium−copper catalysis leading to the disubstituted alkynes 19−28 which after tosylation underwent a novel cyclization under copper catalysis to 2-substituted benzothiazolines 29−38. The expected 3-(arylidine)-2,3-dihydrobenzothiazines were not obtained.