Cobalt-catalyzed regioselective syntheses of indeno[2,1-<i>c</i>]pyridines from nitriles and diynes bearing propargyl fragments
作者:Murong Xu、Zhong Zheng、Mengdan Wang、Lingkai Kong、Yujuan Ao、Yanzhong Li
DOI:10.1039/c8ob02419g
日期:——
highly efficient CoI2/o-phenanthroline catalyzed cycloaddition reaction of diynes bearing TBS protected propargylicalcohol fragments with nitriles has been developed. This methodology offers regioselective access, with good functional group tolerance, to various indeno[2,1-c]pyridine derivatives in moderate to excellent yields. It was found that o-phenanthroline as a bidentate nitrogen ligand showed
已开发出一种高效的CoI 2 /邻菲咯啉催化带有TBS保护的炔丙醇片段的丁炔与腈的环加成反应。该方法以中等至优异的产率提供了对多种茚并[2,1- c ]吡啶衍生物的区域选择性通路,具有良好的官能团耐受性。发现邻菲咯啉作为二齿氮配体在该环加成反应中显示出高功效。
Domino Fragmentations in Traceless Directing Groups of Radical Cascades: Evidence for the Formation of Alkoxy Radicals via C–O Scission
作者:Trevor Harris、Gabriel dos Passos Gomes、Ronald J. Clark、Igor V. Alabugin
DOI:10.1021/acs.joc.6b01052
日期:2016.7.15
Direct evidence for the formation of alkoxy radicals is reported in radical cascades using traceless directing groups. Despite the possibility of hydrogen abstraction in the fragmenting step, followed by loss of R-OH, β-scission is preferred for the formation of alkoxy radicals. For the first time, the C-O radical was intermolecularly trapped using a silyl enol ether. Various C–X fragmenting groups
Facile Synthesis of Polycyclic Fluorene Derivatives<i>via</i>a Palladium-Catalyzed Coupling, Propargyl-Allenyl Isomerization and Schmittel Cyclization Sequence
作者:Ruwei Shen、Linzhu Chen、Xian Huang
DOI:10.1002/adsc.200900600
日期:2009.11
A stepwise process involving Sonogashira coupling, propargyl-allenyl isomerization and Schmittel cyclization has been realized, leading to an efficient synthesis of polycyclic fluorene derivatives from readily available starting materials. The reaction features the formation of three new carbon-carbon bonds to construct the benzene unit together with an efficient assembly of three or four rings in
Traceless Directing Groups in Radical Cascades: From Oligoalkynes to Fused Helicenes without Tethered Initiators
作者:Kamalkishore Pati、Gabriel dos Passos Gomes、Trevor Harris、Audrey Hughes、Hoa Phan、Tanmay Banerjee、Kenneth Hanson、Igor V. Alabugin
DOI:10.1021/ja510563d
日期:2015.1.28
We report the first example of a traceless directing group in a radical cascade. The chemo- and regioselectivity of the initial attack in skipped oligoalkynes is controlled by propargyl OR moiety. Radical translocations lead to the boomerang return of the radical center to the site of initial attack where it assists the elimination of the directing functionality via β-scission in the last step of the cascade. The Bu3Sn moiety continues further via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of skipped oligoalkynes into polycyclic ribbons of tunable dimensions.