Unprecedented stereochemical control in the intramolecular ene-reactions of δ,ε-unsaturated aldehydes using exceptionally bulky organoaluminum reagents: Elucidation of the transition state
作者:Takashi Ooi、Keiji Maruoka、Hisashi Yamamoto
DOI:10.1016/s0040-4020(01)89682-4
日期:——
Unprecedentedstereochemicalcontrol has been achieved in the type II intramolecular ene reactions of δ,ε-unsaturated aldehydes leading to trans-cyclohexanols with excellent selectivity under very mild conditions, using exceptionally bulky methylaluminum bis(4-bromo-2,6-di-tert-butylphenoxide) (MABR). Success of the stereocontrolled cyclization can be ascribable to the ability of this modified organoaluminum
Cobalt-Catalyzed Desymmetric Isomerization of Exocyclic Olefins
作者:Xufang Liu、Xianle Rong、Shihan Liu、Yu Lan、Qiang Liu
DOI:10.1021/jacs.1c11343
日期:2021.12.15
Chiral cyclic olefins, 1-methylcyclohexenes, are versatile building blocks for the synthesis of pharmaceuticals and natural products. Despite the prevalence of these structural motifs, the development of efficient synthetic methods remains an unmet challenge. Herein we report a novel desymmetric isomerization of exocyclicolefins using a series of newly designed chiral cobalt catalysts, which enables
functionalization of styryl carbon-carbon double bonds with triflamide is described viadual visible-light photoredox/cobaloxime catalysis. A range of allylictriflamides (20 examples) were isolated in moderate to good yields (up to 88%) under stoichiometric acceptorless conditions. Dedicated labelling, as well as spectroscopic experiments, enabled to shed light on the concatenated photo- and chemo-catalytic cycles
Aromatization of cyclic hydrocarbons <i>via</i> thioether elimination reaction
作者:Yang Liu、Yingqi Feng、Jinli Nie、Sijie Xie、Xin Pen、Huanliang Hong、Xiuwen Chen、Lu Chen、Yibiao Li
DOI:10.1039/d3cc03279e
日期:——
Herein, the diversity-oriented aromatization of cyclic hydrocarbons via potassium ethyl xanthogenate (EtOCS2K)/NH4I-mediated methylthiyl radical addition and thioether elimination was investigated under transition-metal-free conditions. The methylthiyl radical species were generated in situ via the NH4I-mediated decomposition of DMSO following which EtOCS2K promoted the breaking of carbon–sulfur bonds
在此,研究了在无过渡金属的条件下通过乙基黄原酸钾(EtOCS 2 K)/NH 4 I介导的甲基硫基自由基加成和硫醚消除进行的环烃多样性芳构化。甲硫基自由基是通过NH 4 I 介导的 DMSO 分解原位产生的,随后 EtOCS 2 K 促进硫醚碳硫键的断裂。
Phosphonium Ion-Tethered Secondary Amines for Chemospecific 5-<i>Enolexo</i> Aldol Condensations of 6-Ketoaldehydes
作者:Akash Sugunan、V. M. Aparna、Goreti Rajendar
DOI:10.1021/acs.joc.3c02285
日期:2023.12.15
targets five-membered carbo- and heterocyclic aldehydes, involving unusual aldehydes as donors and ketones as acceptors. Especially, enolizable aryl keto aldehydes and heteroatom-embedded ketoaldehydes exclusively produced cyclized products with our new catalyst, while other catalysts provided predominantly self-aldol or decomposedproducts. The scope and diversity of the method demonstrated by synthesizing