Stereoselectivity in a nitroso-ene cyclization: Formal synthesis of rac-manzacidins A and C
Stereoselectivity in a nitroso-ene cyclization: Formal synthesis of rac-manzacidins A and C
复制标题
亚硝基环化中的立体选择性：rac-manzacidins A 和 C 的正式合成
DOI：
10.1016/j.tet.2018.12.026
复制
发表时间：
2019-03-22
期刊：
影响因子：
2.1
通讯作者：
Hong, Ran
中科院分区：
文献类型：
--
作者：
Liu, Ying;Ruan, Zhuwei;Hong, Ran
亚硝基-烯(NE)反应已被用于构建许多具有生物学意义的化合物的含氮基序。亚硝基是一种瞬时的、高活性的化合物，对于立体控制合成的设计仍然是一个挑战。尽管基于手性助剂的方法已经被开发出来以实现高的非对映选择性，但利用亚硝基化合物固有的手性来进行立体化学控制仍然不发达。我们选择了通过NE环化形成伽马-内酰胺作为研究未来不对称合成的应用原理的基础。本文给出的例子表明，分子内氢键将提供构象约束，通过椅子状的过渡态促进NE反应中优异的表面选择性。空间大的氨基也提供了很好的立体化学控制，可能是通过空间排斥。以下转化得到制备山竹内酯A和C的关键中间体(Ohfune‘s内酯)，从而构成正式合成。(C)2018爱思唯尔有限公司。保留所有权利。
Nitroso-ene (NE) reactions have been adapted in the construction of nitrogen-containing motifs in many biologically interesting compounds. The transient and highly reactive "nitroso" species remains a challenge for designing stereocontrolled syntheses. Although chiral auxiliary-based method has been developed to achieve high diastereoselectivity, the use of the inherent chirality of the nitroso compound for stereochemical control remains underdeveloped. We chose the formation of a gamma-lactam via a NE cyclization as a basis to study the applicable principles for future asymmetric syntheses. The selected examples presented herein reveal that the intramolecular hydrogen bond would provide conformational restraint to facilitate excellent facial selectivity in the NE reaction via a chair-like transition state. The sterically bulky amino group also provides excellent stereochemical control possibly through steric repulsion. The following transformations led to a key intermediate (Ohfune's lactone) in the preparation of manzacidins A and C and thus constitutes a formal synthesis. (C) 2018 Elsevier Ltd. All rights reserved.