Catalyst-controlled reverse selectivity in C–C bond formation: NHC-Cu-catalyzed α-selective allylic alkylation with organolithium reagents
作者:Stefano F. Pizzolato、Massimo Giannerini、Pieter H. Bos、Martín Fañanás-Mastral、Ben L. Feringa
DOI:10.1039/c5cc01521a
日期:——
An efficient and highly [small alpha]-selective copper-catalyzed allylic alkylation of allylic halides with organolithium reagents is presented. The use of N-heterocyclic carbenes as ligands is key to reverse the common [small alpha]-selectivity...
Indium-Promoted Acyloxyallylation Reaction of Azetidine-2,3-diones in Aqueous Media: A New Route to Densely Functionalized 3-Substituted 3-Hydroxy-β-lactams
Denselyfunctionalized3-substituted3-hydroxy-β-lactams have been obtained by acyloxyallylationreaction of azetidine-2,3-diones with 3-bromopropenyl acetate or benzoate in aqueousmedia promoted by indium under Barbier conditions. Two new stereocenters were formed; the stereochemistry at the new C-3 quaternary center was fully controlled by placing a bulky chiral substituent at C-4. However, poor
Highly Efficient Asymmetric Synthesis of Vinylic Amino Alcohols by Zn-Promoted Benzoyloxyallylation of Chiral<i>N</i>-<i>tert</i>-Butanesulfinyl Imines: Facile and Rapid Access to (−)-Cytoxazone
作者:Min Liu、Xing-Wen Sun、Ming-Hua Xu、Guo-Qiang Lin
DOI:10.1002/chem.200900801
日期:2009.10.5
An efficient and convenient α‐hydroxyallylation approach for the asymmetric synthesis of a variety of β‐amino‐α‐vinylalcohols has been successfully developed. A wide range of vinylic amino alcohol derivatives could be obtained in very good yields and with excellent diastereomeric ratios of up to 99:1 in favor of anti isomers by highly diastereoselective Zn‐promoted benzoyloxyallylation of chiral
A concise synthetic route to the conduritols from pentoses
作者:Lise Keinicke、Robert Madsen
DOI:10.1039/b512009h
日期:——
A short synthetic strategy for preparation of the conduritols is described. The key step employs a zinc-mediated fragmentation of protected methyl 5-deoxy-5-iodo-d-pentofuranosides followed by an allylation of the intermediate aldehyde in the same pot. The allylation is performed with 3-bromopropenyl benzoate and occurs with good diastereoselectivity. An amino group can be introduced in the product
A synthetic route to ecteinascidin 743 has been established via an intramolecular cascade Heckreaction to construct the diazabicyclo[3.3.1]nonane skeleton while controlling the two contiguous stereogenic centers. The strategically formed five-membered ring was oxidatively cleaved to generate a dialdehyde intermediate, from which the B ring of ecteinascidin 743 was constructed.
通过分子内级联 Heck 反应构建二氮杂双环[3.3.1]壬烷骨架,同时控制两个相邻的立体中心,建立了海鞘素 743 的合成路线。策略性形成的五元环被氧化裂解,生成二醛中间体,由此构建了海鞘素 743 的 B 环。