Continuous Flow\nNi- or Ru-Zeolite-Catalyzed Intramolecular\nDehydration of Diols and Seco-Acids for Macrocyclic Ethers and Lactones

Herein, we report the efficient intramolecular dehydrative\ncoupling\nof symmetrical and unsymmetrical diols for the synthesis of macrocyclic\ncrown ethers in the presence of Ni-zeolite as a catalyst under continuous\nflow module. This method is also efficient for the intramolecular\ndehydrative macrolactonization of seco-acids using Ni-zeolite or Ru-zeolite.\nThis flow catalysis is demonstrated by a wide substrate scope with\none-time packed Ni-zeolite to produce 20 macrocyclic polyethers and\n11 examples of broad macrolactones with water as a byproduct.