Functionalized tartramides

The preparation of aliphatic, aromatic, or functionalized tartramides directly from tartaric acid and amines under solvent-free conditions and microwave activation was very recently described [67 b],... 

Solvent-free uncatalyzed amidations of acids occurred readily under microwave conditions when conducted with a slight excess of either amine or acid (1.5 equiv). The pathways involved thermolysis of the previously formed ammonium salts (acid-base equilibrium) and proceeded by nucleophilic attack of the amine on the carbonyl moiety of the acid, with removal of water. This procedure was extended to the preparation of functionalized tartramides directly from amines and tartaric acid under solvent-free conditions and microwave activation (Scheme 10). By conventional heating, yields were lower even after 16 h. 

A number of ketones, pharmaceutical compounds, alcohols and hydroxy acids have also been resolved on this phase [724,765-767]. A chiral polysiloxane phase with tartramide substituents has been used for the separation of enantiomers capable of hydrogen bonding interactions with the stationary phase, such as enantiomers containing carboxylic, hydroxyl and amine functional groups [768]. 

A number of other enantloselective processes are known to depend on homochlral acetal or ketal participation. Diols used In these reactions Include tartrate esters, tartramides, propanediols, butanedlols, and pentanedlols. l,4-D1-0-benzyl-L-thre1tol may prove superior to other diols since (a) It can be produced Inexpensively in quantity In either enantiomeric form (b) It Is an amorphous solid (c) It contains a UV chromophore, making derivatives easy to monitor (d) It can be Introduced directly or via transketallzatlon (e) It provides "functionalized arms which can be chemically manipulated after ketallzatlon. 

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