The total synthesis of leukotrienes has been achieved starting from butadiene by a palladium-catalyzed telomerization at room temperature. A Sharpless catalytic asymmetric epoxidation generated the asymmetric centers with >94% ee. Simple transformations of the key intermediate 15 produced the leukotrienes LTA4 methyl ester (4), LTC4 (1), LTD4 (2) and LTE4 (3), as well as (14S,15S)-LTA4 methyl ester (24)
Controlled Payne rearrangements of 2,3-epoxy alcohols in aprotic media: an enantioselective total synthesis of (+)-exo-brevicomin
作者:Philip C. Bulman Page、Christopher M. Rayner、Ian O. Sutherland
DOI:10.1039/c39880000356
日期:——
The catalysis of the isomerisation of primary cis-2,3-epoxy alcohols to threo-1,2-epoxy alcohols by lithium chloride in tetrahydrofuran solution is described; the more reactive terminal epoxides may be selectively trapped in situ by reaction with nucleophiles, and this methodology is used in an enantioselectivesynthesis of (+)-exo-brevicomin.
Zirconium-Mediated S<sub>N</sub>2‘ Substitution of Allylic Ethers: Regio- and Stereospecific Formation of Protected Allylic Amines
作者:Gojko Lalic、Suzanne A. Blum、Robert G. Bergman
DOI:10.1021/ja056132f
日期:2005.12.1
A new zirconium-mediated, regio- and stereospecific SN2' substitution of allylic ethers with a nitrogen nucleophile has been developed. Cbz-protected amine products were isolated in high yield from reactions with a wide range of Z allylic ethers. A mechanism of the allylic substitution consistent with the results of the kinetics and kinetic isotope effect studies was proposed.
已经开发出一种新的锆介导的、区域和立体特异性的 SN2' 取代烯丙醚与氮亲核试剂。从与各种 Z 烯丙基醚的反应中以高产率分离出 Cbz 保护的胺产物。提出了与动力学和动力学同位素效应研究结果一致的烯丙基取代机制。
Scope and Mechanism of Formal S<sub>N</sub>2‘ Substitution Reactions of a Monomeric Imidozirconium Complex with Allylic Electrophiles
作者:Gojko Lalic、Jamin L. Krinsky、Robert G. Bergman
DOI:10.1021/ja7106096
日期:2008.4.1
bromides to give exclusively the products of the SN2' reaction; i.e., attack at the allylic position remote from the leaving group with migration of the doublebond. The primary amine products can be isolated in excellent yields, after in situ Cbz protection, in the presence of variety of functional groups. Good diastereoselectivity and complete stereoselectivity allowed the formation of enantioenriched