Salicylaldehyde reaction with malonic esters

Usually the Knoevenagel condensation yields the unsaturated product, but, with appropriate aldehydes, 3-hydroxymalonates can be isolated.62 The unusual formation of an a-naphthol (74) has been reported from the reaction of diphenylacetaldehyde (73) with diethyl malonate under Knoevenagel conditions.115 Condensation of salicylaldehydes and other aromatic o-hydroxy aldehydes with malonates is still in use for the synthesis of the corresponding coumarin-3-carboxylic esters (75).3<116-118 Reduction... 

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