Alkyne metathesis provided an efficient macrocyclization route to a cycloparaphenyleneacetylene derivative in high yield. The cavity size was suitably matched for C which was tightly bound in an induced-fit fashion. The strained alkynes enabled a copper-free, 3-fold azide-alkyne cycloaddition at 50 °C.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/jacs.6b08752 | DOI Listing |
Org Lett
December 2024
State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China.
The fused eight-membered carbocycles (EMCs) play vital roles in the medicinal and biological investigations of many natural products and marketed drugs. The traditional synthesis of [6-8-6] benzo-fused derivatives involves multistep reactions and low yields, making the development of a one-step synthesis method a more challenging work. Here, we present a novel strategy for one-step construction of [6-8-6] benzo-fused scaffold from propargyl diazoacetates substituted with benzyl-nitrogen heterocyclic ring via Rh(ll)-catalyzed carbene/alkyne metathesis (CAM) and selective C-H bond insertion.
View Article and Find Full Text PDFJ Org Chem
December 2024
College of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an 710021, P. R. China.
Angew Chem Int Ed Engl
November 2024
Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry (AOC), Engesserstr. 15, Geb. 30.45, Karlsruhe, Germany.
The molecular strontium hydride 2 [(Cbz)SrH(L)] (L=benzene, toluene) was isolated and stabilized by employing a sterically demanding carbazole ligand (Cbz=1,8-bis(3,5-ditertbutylphenyl)-3,6-ditertbutylcarbazolyl). Compound 2 was synthesized via phenylsilane metathesis with the corresponding amide (Cbz)SrN(SiMe) and characterized by H NMR, XRD and vibrational spectroscopy methods. We further investigated the stoichiometric reactivity of 2 towards carbon monoxide, azobenzene and trimethylsilylacetylene, showing three distinct reactivity pathways: addition, reduction and deprotonation.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
A low-valent niobium species generated from NbCl and 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (-Me-CHD) in combination with PPh catalyzed a [2+2+1]-cycloaddition reaction of 3,3-disubstituted cyclopropenes and 2 equiv of diaryl/dialkylalkynes, leading to isomeric mixtures of multisubstituted cyclopentadienes -. The initial catalyst activation process was a one-electron reduction of NbCl with -Me-CHD to provide [NbCl(μ-Cl) (L)] (L = PMePh (), L = PPh ()) in the presence of phosphine ligands. An NMR spectroscopic time course experiment using complex as the catalyst revealed an induction period for the product formation, corresponding to an additional one-electron reduction of by the substrates to give catalytically active η-alkyne complexes of NbCl.
View Article and Find Full Text PDFTransition metal-catalyzed alkyne metathesis has become a useful tool in synthetic chemistry. Well-defined alkyne metathesis catalysts comprise alkylidyne complexes of tungsten, molybdenum and rhenium. Non-d Re(v) alkylidyne catalysts exhibit advantages such as remarkable tolerance to air and moisture as well as excellent functional group compatibility.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!