Synthesis of monoazacrown ethers under phase-transfer catalysis.

A procedure has been proposed for the synthesis of monoazacrown ethers by reaction of N-benzyldiethanolamine with oligo(ethylene glycol) bis- p-toluenesulfonates in a two-phase system aromatic hydrocarbon-50% aqueous alkali, followed by removal of the benzyl group by catalytic hydrogenolysis. The maximal yields of N-benzylaza-12-crown-4, -18-crown-6, and -21-crown-7 were achieved by adding 4-10 equiv of LiCl, BaBr, and CsCl, respectively, to the reaction mixture, which probably indicated template effect. [ABSTRACT FROM AUTHOR]