The Use of 3-Hydroxy-2-Methylidene Propionic Acids as Templates

Due to the presence of two functional groups, there is a wide range of possible postmodifications. One possibility is the conversion of the double bond, as in the Michael addition of amines leading to 1,3-amino-alcohols [19], by epoxidation or a Michael addition of a P-ketoester to form pyrazolones [23] after the conversion into hydrazones, followed by an intramolecular cyclization. 

Another possibility is to carry out further reactions involving the hydroxy function, for example in a Mitsunobu reaction [22], In this case, the double bond is rearranged in a manner similar to the synthesis of allylic amines [23], 

The final option is to convert both functional groups in one reaction step. During the synthesis of isoxazolines [24] via a 1,3-dipolar cyclo-addition with nitrile oxides [25], the hydroxy function reacts with phenylisocyanate which is used to dehydrate the nitroalkane to form a carbamate. 

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