- The first squaramide catalyst developed. It functions as a bifunctional catalyst. [3] Some later catalysts are based on such a structure by removing the methylene group on the left to make a 3,5-bis(trifluoromethyl)phenyl-group or adding a 6-methoxy group on the quinoline. [1]
- Zlotin's bifunctional squaramide catalyst. [1]