Synthesis of benzothiazolyl coumarin with propargyl group.

(i) NaBH(OAc)3, acetone, rt, 12 h, 78%. (ii) propargyl chloride, Hunig’s base, toluene, rt, 10 h, 89%. (iii) POCl3, DMF, rt, 12 h, 82%. (iv) ethyl 2-(benzo[d]thiazol-2-yl)acetate, piperidine, ethanol, reflux, 2 h, 50%.