Source of materialA mixture of CuI (0.2 mmol) and benzthiazoline-2-thione (0.2 mmol) in MeOH and CH 2 Cl 2 (10mL, v/v = 1:1) was stirred for 2h. PPh 3 (0.2 mmol) was added to the mixture, which was stirred for another 4h. The insoluble residues were removed by filtration, and the filtrate was evaporated slowly at room temperature for a week to yield colourless crystalline products.