New Anionic Cyclization of 4- and 5-Alkynylamines: Synthesis of 2-Benzylidene Pyrrolidines and Piperidines
摘要:
Treatment of 4- and 5-alkynylamines with 0.5-1.2 equiv. of butyllithium brought about a facile anionic cyclization, giving the corresponding enamine pyrrolidines and piperidines having an exo double bond in high yields. Treatment of 4-alkynamides with lithium aluminum hydride also gave the similar enamine pyrrolidines in high yields.
Enantioselective Conia-Ene-Type Cyclizations of Alkynyl Ketones through Cooperative Action of B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <i>N</i>-Alkylamine and a Zn-Based Catalyst
作者:Min Cao、Ahmet Yesilcimen、Masayuki Wasa
DOI:10.1021/jacs.8b13757
日期:2019.3.13
An efficient and highly enantioselective Conia-ene-type process has been developed. Reactions are catalyzed by a combination of B(C6F5)3, an N-alkylamine and a BOX-ZnI2 complex. Specifically, through cooperative action of B(C6F5)3 and amine, ketones with poorly acidic α-C-H bonds can be converted in situ to the corresponding enolates. Subsequent enantioselective cyclization involving a BOX-ZnI2-activated
C−C Bond-Forming Strategy by Manganese-Catalyzed Oxidative Ring-Opening Cyanation and Ethynylation of Cyclobutanol Derivatives
作者:Rongguo Ren、Zhen Wu、Yan Xu、Chen Zhu
DOI:10.1002/anie.201510973
日期:2016.2.18
cyano C1 unit and ethynyl C2 unit are regiospecifically introduced to the γ‐position of ketones at room temperature, providing a mild yet powerful method for production of elusive aliphatic nitriles and alkynes. All transformations described are based on a common sequence: 1) oxidative ring‐opening of cyclobutanol substrates by C−C bond cleavage; 2) radical addition to triple bonds bearing an arylsulfonyl
New synthetic approaches for the synthesis of indoloquinolines and carbocycle-fused quinolines have been developed employing alkynylketone substrates. These synthetic transformations involved the application of N2-extrusion of azido complexes as a key step to generate carbodiimidium ion and nitriliumion in situ, which further cyclized intramolecularly with alkyne via a domino process to provide indoloquinolines
Formal γ-alkynylation of ketonesvia Pd-catalyzed C–C cleavage
作者:Asraa Ziadi、Arkaitz Correa、Ruben Martin
DOI:10.1039/c2cc37281a
日期:——
A formal gamma-alkynylation of ketones via Pd-catalyzed C-Cbond-cleavage is presented. The method allows for the coupling of tert-cyclobutanols and bromoacetylenes, giving access to versatile alkynes that are beyond reach otherwise.
Alkynylation of Tertiary Cycloalkanols via Radical C–C Bond Cleavage: A Route to Distal Alkynylated Ketones
作者:Shun Wang、Li−Na Guo、Hua Wang、Xin-Hua Duan
DOI:10.1021/acs.orglett.5b02353
日期:2015.10.2
An efficient Na2S2O8-promoted radical coupling of tertiary cycloalkanols with alkynyl hypervalent iodide reagents via C-C bond cleavage was developed. This tandem ring-opening/alkynylation procedure showed some advantages, including mild conditions and wide substrate scope, thus providing a simple synthetic method for beta-, gamma- and delta-alkynylated ketones.