copper-catalyzed C–S or C–Se bond formation between aryl iodides and easily available chalcogen sources leading to diaryl chalcogenides is reported. A variety of symmetrical diaryl sulfides and diaryl selenides were synthesized in good to excellent yields. Unsymmetrical diaryl sulfides were also obtained in moderate yields from two different aryl iodides by a one-pot tandem process. This strategy was
Rapid Access to Dibenzohelicenes and their Functionalized Derivatives
作者:Andrej Jančařík、Jiří Rybáček、Kevin Cocq、Jana Vacek Chocholoušová、Jaroslav Vacek、Radek Pohl、Lucie Bednárová、Pavel Fiedler、Ivana Císařová、Irena G. Stará、Ivo Starý
DOI:10.1002/anie.201301739
日期:2013.9.16
Spiraling up: Easy access to dibenzo[5]‐, dibenzo[6]‐, and dibenzo[7]helicenes (see picture) as well as their functionalizedderivatives includes Sonogashira and Suzuki–Miyaura couplings, desilylation, and [2+2+2] alkyne cycloisomerization. The simplicity of this non‐photochemical approach combined with the potential for helicity control favors dibenzohelicenes over the parent helicenes for practical
A hexadehydro-Diels–Alder reaction was demonstrated on-surface in single molecules of a cyclic strained triyne. The starting material, several intermediates and the product were visualized by means of atomic force microscopy (AFM) with CO-functionalized tips. Our results pave the way to use this iconic pericyclic reaction for on-surface synthesis, introducing the concept of atom economy in the field
在环状应变三炔的单分子表面上证明了十六氢-狄尔斯-阿尔德反应。通过带有 CO 功能化尖端的原子力显微镜 (AFM) 观察起始材料、几种中间体和产物。我们的结果为使用这种标志性的周环反应进行表面合成铺平了道路,在该领域引入了原子经济的概念。
Preparation and Reactions of Mono- and Bis-Pivaloyloxyzinc Acetylides
作者:Carl Phillip Tüllmann、Yi-Hung Chen、Robin J. Schuster、Paul Knochel
DOI:10.1021/acs.orglett.8b01892
日期:2018.8.3
Mono-pivaloyloxyzinc acetylide and bis-pivaloyloxyzinc acetylide were selectively prepared from ethynylmagnesium bromide in quantitative yields. These zinc reagents readily underwent Negishi cross-couplings with (hetero)aryl iodides or bromides as well as subsequent Sonogashira cross-couplings. 1,3-Dipolar cycloadditions of these zinc acetylides with benzylic azides produced zincated and bis-zincated
Dihalodiphenylacetylenes are conveniently synthesized by a doubleelimination reaction of β-substituted sulfones which are readily obtained from halogen-substituted benzyl sulfone and benzaldehyde derivatives. Halogens can be incorporated at any desired positions in the diphenylacetylene skeleton simply by choosing the substitution position of the halogen on the aromatic rings of the starting compounds