Asymmetric induction during photocyclization of chiral and achiral α-oxoamides within achiral zeolites
作者:Arunkumar Natarajan、V. Ramamurthy
DOI:10.1039/b611387g
日期:——
gamma-hydrogen transfer. While in benzene the major product is oxazolidinone, within an MY zeolite, the main product is a beta-lactam. In this investigation, we have focused our attention on asymmetricinduction in the formation of the beta-lactam product. Two approaches--using a chiral inductor and chiral auxiliary--have been employed. While in solution, in the presence of chiral inductors, achiral
Control of Enantioselectivity in the Photochemical Conversion of α-Oxoamides into β-Lactam Derivatives
作者:Arunkumar Natarajan、Keyan Wang、V. Ramamurthy、John R. Scheffer、Brian Patrick
DOI:10.1021/ol025700i
日期:2002.5.1
[reaction: see text]. Several approaches to asymmetricinduction in the alpha-oxoamide (1) to beta-lactam (2) photorearrangement are described. Best results are obtained via irradiation of ionic and covalent chiral auxiliary-containing reactants in the crystallinestate and in the interior supercages of zeolites.
Asymmetric Induction during Yang Cyclization of α-Oxoamides: The Power of a Covalently Linked Chiral Auxiliary Is Enhanced in the Crystalline State
作者:Arunkumar Natarajan、Joel T. Mague、V. Ramamurthy
DOI:10.1021/ja043999p
日期:2005.3.1
Gamma-hydrogen abstraction has been revealed to be the primary photoprocess in the crystallinestate of alpha-oxoamides through photochemical and X-ray structural studies. The outstanding ability of a covalent chiral auxiliary in generating asymmetricinduction in the photoproduct beta-lactam has been established with 10 examples. We have shown that the crystal lattice preorganizes the reactant molecules
通过光化学和 X 射线结构研究,γ-氢提取已被揭示是 α-氧代酰胺结晶状态的主要光处理过程。共价手性助剂在光产物 β-内酰胺中产生不对称诱导的杰出能力已通过 10 个例子得到证实。我们已经表明,晶格将反应物分子预组织为 β-内酰胺的单个非对映异构体,并防止 1,4-双基中间体的大运动,这将导致立体化学记忆的丧失。所研究的一个实例的罕见单晶到单晶转化路径建立了反应物和产物的立体化学之间的直接相关性。
Cation–π interactions as a tool to enhance the power of a chiral auxiliary during asymmetric photoreactions within zeolites
作者:Lakshmi S. Kaanumalle、J. Sivaguru、N. Arunkumar、S. Karthikeyan、V. Ramamurthy
DOI:10.1039/b209810e
日期:——
Owing to the existence of cationâÏ interactions, aryl chiral auxiliaries perform far better than alkyl chiral auxiliaries during asymmetric photoreaction.