Tandem Transformations via Friedel–Crafts Acylation Followed by a Ring-Expansion, Ring-Opening, and Cycloisomerization Sequence
作者:Hun Young Kim、Kyungsoo Oh
DOI:10.1021/acs.orglett.8b03881
日期:2019.2.1
A tandem synthetic route to a diverse array of cyclic compounds has been developed from Friedel–Craftsacylation of alkynes followed by the microwave irradiation of β-chlorovinyl ketone intermediates. The stereoisomeric β-chlorovinyl ketone intermediates smoothly underwent a thermal α-vinyl enolization and ring expansion to vinyl and carbocyclic furans as well as cyclopetene derivatives in good to
Studies on Elimination Pathways of β-Halovinyl Ketones Leading to Allenyl and Propargyl Ketones and Furans under the Action of Mild Bases
作者:Hun Young Kim、Jian-Yuan Li、Kyungsoo Oh
DOI:10.1021/jo302253c
日期:2012.12.21
stereochemically defined β-halovinyl ketones has been investigated using a mild base, NEt3, leading to the formation of allenyl ketones and propargyl ketones. A preferential α-vinyl enolization of (E)-β-chlorovinyl ketones has been observed where a nonplanar s-cis conformation is proposed as a dominant conformation as opposed to a planar s-cis conformation of (Z)-β-chlorovinyl ketones. Other eliminative pathways
1,3-Dienones and 2<i>H</i>-Pyran-2-ones from Soft α-Vinyl Enolization of β-Chlorovinyl Ketones: Defined Roles of Brönsted and Lewis Base
作者:Hun Young Kim、Kyungsoo Oh
DOI:10.1021/acs.orglett.5b03265
日期:2015.12.18
The eliminative reaction pathways of (E)-β-chlorovinyl ketones were investigated in the presence of both Brönsted and Lewis bases. The Brönsted base, Et3N, effected the soft α-vinyl enolization of (E)-β-chlorovinyl ketones to [3]cumulenol intermediates; in turn, a catalytic amount of Lewis base, PPh3, initiated isomerization to provide 1,3-dienones in high yields. The introduction of a carbon-based
在布朗斯台德碱和路易斯碱的存在下研究了(E)-β-氯乙烯基酮的消除反应途径。布朗斯台德碱Et 3 N影响了(E)-β-氯乙烯基酮向[3]异丙苯三酚中间体的软α-乙烯基烯醇化作用。进而,催化量的路易斯碱PPh 3引发了异构化反应,以高收率提供了1,3-二烯酮。将碳基亲核试剂引入反应混合物中,可在一锅中高效合成2 H -pyran-2-one,其中碳基亲核试剂是由额外等价的布朗斯台德碱Et 3生成的N,攻击亲电的[3]枯烯酚中间体以起始环化,得到2 H-吡喃-2-酮。
A facile synthesis of 3,4-dimercaptofurans via sulfenylation of (E)-β-chlorovinyl ketones and 1,2-sulfur migration
作者:E. Song、H. Y. Kim、K. Oh
DOI:10.1039/c6ob02772e
日期:——
The one-pot sulfenylation of (E)-β-chlorovinyl ketones was investigated under soft α-vinyl enolization conditions. Modulating the nature of nucleophilic species using a “hard” base the regioselective formation of α,γ-dithio-allenyl ketones has been achieved, where the thermodynamic control was mimicked by the presence of Et3N·HCl. The sulfenylated products, α,γ-dithio-allenyl and α,α-dithio-propargyl
Ambivalent Reactivity Modes of β-Chlorovinyl Ketones: Electrophilic Lithium [3]Cumulenolates from Soft Vinyl Enolization Strategy
作者:Hun Young Kim、Edward Oscar Rooney、Raymond Phillip Meury、Kyungsoo Oh
DOI:10.1002/anie.201302750
日期:2013.7.29
Soft spot: The softvinylenolization of (E)‐β‐chlorovinyl ketones results in the in situ generation of electrophiliclithium [3]cumulenolates, which react with nucleophiles such as another lithium [3]cumulenolate to stereoselectively form vinyl allenones. They can also react with ketimine esters to give 3‐methylenepyrrolidines.