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An improved method for the synthesis of formyl derivatives of N-methylbenzoazacrown ethers is proposed. They are prepared in up to 68% yields over fewer steps and with a much shorter time required for the last step. The stability constants of complexes formed by N-methylbenzoazacrown ethers and their structural analogs with alkali metal, alkaline-earth metal and ammonium cations were determined by 1H NMR titration in CD3CN. High stability of complexes of N-methyl derivatives of benzoazacrown ethers is demonstrated, comparable with or even exceeding the stability of benzocrown-ether complexes and markedly exceeding the stability of complexes of phenylazacrown ethers with the same macrocycle size. The structures of azacrown ethers and their complexes with Ba(ClO4)2 were studied by X-ray diffraction. A high degree of pre-organization of N-methylbenzoazacrown ethers toward the formation of complexes with metal and ammonium cations was noted, which is due to the clear-cut pyramidal geometry of the nitrogen atom and the orientation of the lone electron pairs (LEPs) of most heteroatoms towards the centre of the macroheterocycle. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]