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首页> 外文期刊>Chemistry: A European journal >A Novel Multistep Mechanism for the Stereocontrolled Ring Opening ofHindered Sulfamidates: Mild, Green, and Efficient Reactivity with Alcohols
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A Novel Multistep Mechanism for the Stereocontrolled Ring Opening ofHindered Sulfamidates: Mild, Green, and Efficient Reactivity with Alcohols

机译：阻抑的氨基磺酸酯立体控制开环的新型多步机制：与酒精的温和，绿色和高效反应性

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摘要

Cyclic hindered sulfamidatesexhibited an outstanding performancein their ring-opening reactions with al-cohols and in the absence of any exter-nal activator. The mechanism of thisunprecedented transformation wasthoroughly studied both experimentallyand theoretically. As a result, a nontri-vial stepwise pathway involving sol-vent-induced conversion of the sulfami-dates to activated aziridinium and thento oxazolinium cations, which are final-ly opened at their 5-position with inver-sion of configuration, is proposed. The presence of the SO_3moiety in the sul-famidate was revealed as a "built-in ac-tivator". In fact, the spontaneous SO3cleavage takes place under the reactionconditions and avoids the subsequentstep of hydrolysis after the ring open-ing of the sulfamidates. This is anotherimportant improvement of this meth-odology with respect to the standardbasic conditions, allowing a greatercompatibility with other functionalgroups. Furthermore, the carbamategroup plays a key role in this mecha-nism. Briefly, a highly chemoselectiveand stereoespecific formal solvolysis ofhindered sulfamidates with alcoholswithout further activation is described.This reaction takes place exclusively atthe quaternary center with inversion ofconfiguration, providing a new straight-forward synthetic route to 0-substitut-ed a-methylisoserines.
机译：环状受阻的氨基磺酸盐在与乙醇的开环反应中和没有任何外部活化剂的情况下表现出出色的性能。在实验和理论上都深入研究了这种前所未有的转化机理。结果，提出了一种非简单的逐步途径，该途径涉及溶剂诱导的氨基磺酸盐到活化的叠氮鎓然后到恶唑啉鎓阳离子的溶剂-诱导的转化，它们最终在其5-位打开，且构型颠倒。 。磺酰胺中的SO_3部分的存在被揭示为“内置活性剂”。实际上，在反应条件下发生了自发的SO3裂解，避免了氨基磺酸酯开环后的后续水解步骤。这是该方法相对于标准基本条件的另一个重要改进，它可以与其他官能团更好地兼容。此外，氨基甲酸酯基团在该机制中起关键作用。简而言之，描述了受阻的氨基磺酸盐与醇的高度化学选择性和立体定向的正式溶剂分解反应，无需进一步活化。该反应仅在四元中心发生，且构型反转，提供了一种新的直接合成路线，可合成0取代的α-甲基异丝氨酸。

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