Heteroannulation through copper catalysis: a novel cyclization leading to a highly regio- and stereoselective synthesis of 2-substituted benzothiazolines
[reaction: see text] 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.