Polyethylene glycol (PEG), an excellent substitute for crown ethers, has been successfullly used as a co-solvent in some substitution reactions, 1-6) catalytic hydrogenations, 7, 8) oxidation reactions, S) and reductions. 9, 10) In this paper, we describe an improved and efficient synthesis of 2-cyano-6-methoxybenzothiazole (2), a key intermediate for firefly luciferin synthesis, from commercially available 2-amino-6-methoxybenzothiazole (4) by a ...