Diastereomeric 2-aminomethyl-1,4-benzodioxane mandelates: phase diagrams and resolution

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• 作者：Cristiano Bolchi ; Marco Pallavicini ; Laura Fumagalli ; Paola Ruggeri ; Ermanno Valoti
• 刊名：Tetrahedron: Asymmetry
• 出版年：2013
• 出版时间：31 July, 2013
• 年：2013
• 卷：24
• 期：13-14
• 页码：796-800
• 全文大小：556 K

文摘

The diastereomeric salts of (R)- and (S)-2-aminomethyl-1,4-benzodioxane with unichiral mandelic acid form a simple eutectic, whose binary phase melting point diagram shows the unique eutectic at 0.35 M ratio of the less soluble diastereomer. Such an eutectic composition, near to 0.5, is consistent with the modest efficiency previously reported for their separation via crystallization from ethanol/ethyl acetate. However, the ternary solubility phase diagram, obtained from solubility measurements in methanol, shifts the eutectic to a lower molar ratio (0.10) of the less soluble diastereomer, thus indicating an optimal resolvability of the diastereomeric mandelates. This was confirmed by the highly efficient resolution of racemic 2-aminomethyl-1,4-benzodioxane with (R)-mandelic acid via a single crystallization from methanol. The ready availability of both the racemic substrate and the resolving acid makes this simple and efficient resolution procedure very attractive to obtain the enantiomers of 2-aminomethyl-1,4-benzodioxane, which are important synthetic intermediates.