Multi-gram syntheses of four crown ethers using K+ as templating agent

Dibenzo-30-crown-10 (DB30C10, 1c), dibenzo-24-crown-8 (DB24C8, 1a), 4-carbomethoxydibenzo-24crown-8 (1b) and a new crown ether, 4-carbomethoxydibenzo-30-crown-10 (1d), were synthesized by a simple, high yielding, three-step method. Potassium ions from the highly soluble KPF6 were employed to template the cyclization step, which resulted in very high isolated yields (80–90%).

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