Effect of Chain Length on Radical to Carbanion Cyclo-Coupling of Bromoaryl Alkyl-Linked Oxazolines: 1,3-Areneotropic Migration of Oxazolines
作者:Laura J. Marshall、Mark D. Roydhouse、Alexandra M. Z. Slawin、John C. Walton
DOI:10.1021/jo0620720
日期:2007.2.1
2-(1-phenyl-1,2,3,4-tetrahydronaphthalen-1-yl)-2-oxazoline, respectively. The major products from the precursor with a 5-C-atom spacer were derivatives of benzocycloheptane in which the oxazoline group had undergone a novel areneotropic migration from the end of the spacer to the benzo ring. The product from reaction of the corresponding 2-C-atom precursor was a 9-oxazolinophenanthrene derivative. EPR
制备了具有2至6个C原子(n = 0-4)的烷基间隔基的2-卤苯基烷基-2-恶唑啉,其S RN考察了几种基本系统的1型反应。促进与相应的苯并环烷烃衍生物进行环偶联的最佳条件涉及在THF中使用LDA。具有3-C原子和4-C原子间隔基的前体可得到2-(1'-苯基茚满-1'-基)-2-恶唑啉和2-(1-苯基-1,2,3,分别为4-四氢萘-1-基)-2-恶唑啉。具有5-C原子间隔基的前体的主要产物是苯并环庚烷的衍生物,其中恶唑啉基团从间隔基的末端到苯并环经历了新的各向异性吸附。相应的2-C原子前体的反应产物是9-恶唑啉代菲衍生物。EPR光谱表明,LDA促进反应的中间体是产物苯并环烷烃的自由基阴离子。这支持一个SRN 1型链机制涉及通过间隔基团连接到氮杂酸酯离子的芳基的初始产生。分子内自由基与碳负离子的偶联随后产生了闭环的苯并环烷烃自由基阴离子,该阴离子将电子转移到更多的前体上。用含有手性2-恶唑啉