Enantioselective Pallada‐Electrocatalyzed C−H Activation by Transient Directing Groups: Expedient Access to Helicenes
作者:Uttam Dhawa、Cong Tian、Tomasz Wdowik、João C. A. Oliveira、Jiping Hao、Lutz Ackermann
DOI:10.1002/anie.202003826
日期:2020.8.3
Asymmetric pallada‐electrocatalyzed C−H olefinations were achieved through the synergistic cooperation with transient directing groups. The electrochemical, atroposelective C−H activations were realized with high position‐, diastereo‐, and enantio‐control under mild reaction conditions to obtain highly enantiomerically‐enriched biaryls and fluorinated N−C axiallychiral scaffolds. Our strategy provided
Synthesis of [5]-, [6]-, and [7]Helicene via Ni(0)- or Co(I)-Catalyzed Isomerization of Aromatic <i>cis</i>,<i>cis</i>-Dienetriynes
作者:Filip Teplý、Irena G. Stará、Ivo Starý、Adrian Kollárovič、David Šaman、Lubomír Rulíšek、Pavel Fiedler
DOI:10.1021/ja0259584
日期:2002.8.1
syntheses of the parent [5]helicene (2), 7,8-dibutyl[5]helicene (23), [6]helicene (24), and [7]helicene (25). The approach can be adapted to prepare functionalized helicenes as exemplified by the eight-step synthesis of 7,8-dibutyl-2,3-dimethoxy[6]helicene (34). Density functional theory (DFT) calculations showed that bis[2-((1Z)-1-buten-3-ynyl)phenyl]acetylene (1) and isomeric [5]helicene (2) differ enormously
Synthesis of Derivatives of Phenanthrene and Helicene by Improved Procedures of Photocyclization of Stilbenes
作者:Harish R. Talele、Monik J. Gohil、Ashutosh V. Bedekar
DOI:10.1246/bcsj.82.1182
日期:2009.9.15
An improved method has been developed for photocyclization of stilbene to construct phenanthrenes and benzo[c]phenanthrenes. This reaction is promoted by iodine while tetrahydrofuran is used as an ...
A facile synthesis of carbo- and heterohelicenes was achieved via tandem cycloaromatization of bisacetal precursors, which were readily prepared through C–C bond formation by Suzuki–Miyaura coupling. This cyclization was efficiently realized by a catalytic amount of trifluoromethanesulfonic acid (TfOH) in a cation-stabilizing solvent, 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP), which readily allowed
We have discovered a dual (i. e., soft and hard) Lewisacidity of alumina that enables rapid one-pot π-extension through the activation of terminal alkynes followed by C-F activation. The tandem reaction introduces an acenaphthene fragment - an essential moiety of geodesic polyarenes. This reaction provides quick access to elusive non-alternant polyarenes such as π-extended buckybowls and helicenes