Microwave synthesis of cucurbit[n]urils

Background: Cucurbit[n]urils (CB[n]; n = 5, 6, 7, 8 or 10) are a family of macrocycles made from the acid-catalyzed condensation of glycoluril and formaldehyde. Results: The synthesis of CB[n] using microwave radiation has been examined and the effect of acid type, reaction time and temperature on the distribution of products has been determined. Synthesis in HCl yields CB[5], CB[6], CB[7] and CB[8] in 10 min and is most efficient at 160 degrees C. Synthesis in H2SO4 yields mostly CB[6] in 3 min and is most efficient at 160 degrees C. Conclusion: Microwave synthesis provides an efficient and cost-effective method for the large-scale production of CB[n] for a range of applications, particularly drug delivery.