A Rapid Access to Biaryl Ether Containing Macrocycles by Pairwise Use of Ugi 4CR and Intramolecular SNAr-Based Cycloetherification

An Ugi reaction promoted by ammonium chloride in aprotic solvent is documented here for the first time. From readily accessible starting materials, macrocycles with an endo aryl-aryl ether bond are synthesized in only two steps, Ugi four-component reaction (Ugi 4CR) and an intramol. SNAr reaction. The nitro group serves as an activator for the macrocyclization and provides a handle for the introduction of functional group diversity. For example, dipeptide amide I was obtained in an Ugi 4CR from isonitrile II, PhCHO, PhCH2NH2 and 3-hydroxyphenylacetic acid in the presence of NH4+Cl- in toluene at 0 Deg for 20 h. Cycloetherification of I took place in the presence of K2CO3 in DMF for 3 h to give macrocycle III in 80% yield. [on SciFinder (R)]