An Efficient Method of Removing Chiral 2-Oxazolidinone Auxiliaries in a Methoxide-Carbonate System. Its Optimization and Synthetic Application

我们在过量碳酸二甲酯存在的情况下，通过与NaOMe的反应，完成了N-酰基-2-恶唑烷酮和N-（2-羟乙基）酰胺的N-酰基键的高效裂解，实现了这些手性助剂的清洁去除。这些反应通常在温和的条件下进行，以高产出相应的甲酯。这里所描述的N-酰基键劈裂对于具有邻近N-酰基-2-恶唑烷酮或N-（2-羟乙基）酰胺的季碳或氨基羰基的立体要求高的分子，以及对于热力学不稳定的分子，如具有平面、轴向或斜向手性的atropisomer化合物，在较高温度下面临异构化的风险特别有用。

We have accomplished the efficient N-acyl bond cleavage of both N-acyl-2-oxazolidinone and N-(2-hydroxyethyl)amide based on the reaction with NaOMe in the presence of excess dimethyl carbonate to accomplish a clean removal of those chiral auxiliaries. These reactions generally proceed under mild conditions to give the corresponding methyl esters in high yields. The N-acyl bond cleavage described here are especially useful for sterically demanding molecules with quaternary carbons neighboring exocyclic or carbamoyl carbonyl of N-acyl-2-oxazolidinones or N-(2-hydroxyethyl)amides and for thermodynamically less stable molecules such as atropisomeric compounds with planar, axial, or herical chirality, which face a risk of isomerization at higher temperatures.