Abstract
A four‐component one‐pot transformation involving the Passerini reaction, an aldol addition, and a transesterification has been elaborated, providing an access to a library of densely functionalized tartaric acid derivatives. Two modifications of the process have been explored. In the first modification, carboxylic acids and isocyanides were treated with an excess of ethyl glyoxalate leading to the incorporation of two ethyl glyoxalate residues in the resulting post‐Passerini products. The second modification involved the initial reaction of a carboxylic acid, an aryl glyoxal and an isocyanide to form the Passerini adduct. This was followed by the in situ addition of ethyl glyoxalate to produce the second type of post‐Passerini products through aldol addition and transesterification.