View all references ] Classical methods that are used for their synthesis include aldol, Claisen–Schmidt, [ 2 2. For reviews, see (a) Nielsen , AT ; Houlihan , WJ The aldol condensation . Org. React. 1968 , 16 , 1 ; (b) House, HO Modern Synthetic Reactions, 2nd ed.; WA Benjamin: Menlo Park, CA, 1972; 632–639; (c) For recent examples of the Claisen–Schmidt condensation, see Choudary , BM ; Kantam , ML ; Ranganath , KVS ; Mahender , K. ; ...