Synthesis of partially methyl substituted cucurbit[n]urils with 3a-methyl-glycoluril

Two partially methyl substituted cucurbituril, PMeQ[5] and HMeQ[6], were synthesized from 3a-methyl-glycoluril. They were characterized by 1H NMR, ES-MS and single crystal X-ray diffraction. Ab initio calculations showed that each isolated methyl substituted cucurbit[n]uril is the most stable form among its all possbile isomers. One of the remarkable properties of these two partially substituted cucurbituril is their high solubility in the commonly used solvents such as water, methanol, and DMSO.