Ellis Trevor K, Ueki Hisanori, Yamada Takeshi, Ohfune Yasufumi, Soloshonok Vadim A
Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA.
J Org Chem. 2006 Oct 27;71(22):8572-8. doi: 10.1021/jo0616198.
A new generation of modular achiral glycine equivalents have been evaluated with respect to their synthetic utility for the production of tailor-made, sterically constrained alpha-amino acids, which proved to be the most efficient approach developed to date for the synthesis of symmetrical alpha,alpha-disubstituted-alpha-amino acids. Among the new series of achiral glycine equivalents, one was found to be a superior glycine derivative for the Michael additions with various (R)- or (S)-N-(E-enoyl)-4-phenyl-1,3-oxazolidin-2-ones representing a general and practical synthesis of sterically constrained beta-substituted pyroglutamic acids. In particular, the application of these complexes allowed for the preparation of several beta-substituted pyroglutamic acids which include electron-releasing and sterically demanding substituents in the structure thus increasing the synthetic efficiency and expanding the generality of these Michael addition reactions.
新一代模块化非手性甘氨酸等价物已就其在生产定制的、空间受限的α-氨基酸方面的合成效用进行了评估，事实证明这是迄今为止开发的用于合成对称α,α-二取代-α-氨基酸的最有效方法。在新的一系列非手性甘氨酸等价物中，有一种被发现是用于与各种（R）-或（S）-N-（E-烯酰基）-4-苯基-1,3-恶唑烷-2-酮进行迈克尔加成反应的优良甘氨酸衍生物，这代表了一种通用且实用的空间受限β-取代焦谷氨酸的合成方法。特别是，这些配合物的应用使得能够制备几种β-取代焦谷氨酸，其结构中包括供电子和空间要求高的取代基，从而提高了合成效率并扩大了这些迈克尔加成反应的通用性。
