# Why is DBU the most popular base with an amidino group? Does the basic strength have something to do with the ring size being 7 for one of the rings?

Structure of DBU

DBU is used as a very strong base(which is due to resonance stabilization of amidinium cation) with steric bulk. Is any other compound used instead? If not, why not?

• DBN is used, too. – EJC Apr 9 '16 at 13:42
• Caprolactam is $38/kg from Aldrich. Acrylonitrile is$55 for two liters. My guess: it's cheaper to make than similar ring sizes. I know valerolactam is significantly more expensive than \$38/kg. – SendersReagent Apr 9 '16 at 14:17
• What does the price of lactams have to do with price of amidines ? – gluco Apr 10 '16 at 16:15
• @gluco Caprolactam + acrylonitrile = starting materials for DBU. Imagine caprolactam with a nitrogen in place of the oxygen and three more carbons, then cyclized. – SendersReagent Apr 13 '16 at 12:50