coupling of ω‐allenyl‐substituted carboxylicacids. The use of a modified diop ligand, chiral DTBM‐diop, led to high enantioselectivity (up to 93 % ee). The reaction tolerated a large variety of functionalities, including α,β‐unsaturated carboxylicacids and depsipeptides, and provided the desired macrocycles with very high enantio‐ and diastereoselectivity.
Novel aryl aliphatic acids or derivatives thereof of the general formula R--(C.sub.x --C.sub.y)--(C.sub.m H.sub.2m)--G--C(R.sup.1).sub.2 --Ar--(C.sub.n H.sub.2n)--COOR.sup.2 are described which exhibit inhibiting activity against 12-lipoxygenase. The compounds are characterized by having a low level of toxicity. Also included are salts and esters of the aliphatic acids.
Scope and Limitations of Lithium-Ethylenediamine-THF-Mediated Cleavage at the α-Position of Aromatics: Deprotection of Aryl Methyl Ethers and Benzyl Ethers under Mild Conditions
作者:Takeshi Sugai、Takeyuki Shindo、Yasuaki Fukuyama
DOI:10.1055/s-2004-815977
日期:——
and limitation of lithium-ethylenediamine-THF-mediated reductive bond cleavage at the α-position of aromatics were examined. Very mild conditions such as lithium metal (5 equiv) and ethylenediamine (7 equiv) in oxygen-free THF were quite effective for the demethylation of aromaticethers even at as low as -10 °C. Allyl benzyl ethers were also deprotected under these conditions with very little change
Chiral Bifunctional Phosphine Ligand Enables Gold-Catalyzed Asymmetric Isomerization and Cyclization of Propargyl Sulfonamide into Chiral 3-Pyrroline
作者:Xinpeng Cheng、Liming Zhang
DOI:10.1021/acs.orglett.1c02896
日期:2021.11.5
This work details an asymmetric gold-ligand cooperativecatalysis that transforms readily accessible chiral/achiral propargylic sulfonamides into chiral 3-pyrrolines. A bifunctional biphenyl-2-ylphosphine ligand featuring a chiral tetrahydroisoquinoline fragment is essential for the observed metal–ligand cooperation and the asymmetric induction. 2,5-cis-3-Pyrrolines are formed with excellent diastereoselectivities
Towards the synthesis of epothilone A: Enantioselective preparation of the thiazole sidechain and macrocyclic ring closure
作者:Richard E. Taylor、Jeffrey D. Haley
DOI:10.1016/s0040-4039(97)00285-2
日期:1997.3
A synthetic approach to a new class of microtubule-stabilizing natural products is described which employs a macrocyclic olefination strategy to cyclize the 16-membered lactone ring. The C13C19 thiazole subunit of epothilone A and B is prepared in high enantioselectivity using a catalytic asymmetric allylation reaction.