The ruthenium-catalyzed hydrocarbamoylative cyclization of 1,6-diynes with formamides afforded exocyclic-diene-type α,β,γ,δ-unsaturated amides with 100% stereoselectivity. A plausible mechanism involving ruthenium hydride species is proposed to explain the experimental results. Some control experiments, performed using DMF-d7 and/or D2O, corroborate the proposed mechanism.
The use of N‐(p‐chlorophenyl)methylbenzoxazole‐2‐thione as a sulfur‐atom donor enables the catalytic [2+2+1] cycloaddition of diynes in wet DMF at 80 °C when open to air, thus affording diverse fused thiophenes with good yields and wide functional‐group compatibility. A plausible mechanism, involving a cationic ruthenacycle intermediate, was also proposed on the basis of several control experiments
A Combined Transition-Metal-Catalyzed and Photopromoted Process: Synthesis of 2,3-Fused 4-Phenylnaphthalen-1-yl Carboxylates from 1,7-Diaryl-1,6-diynes
2,3‐Fused 4‐phenylnaphthalen‐1‐yl carboxylates were synthesized in a step‐ and atom‐economical manner using a ruthenium‐catalyzed hydrocarboxylative cyclization of 1,7‐diaryl‐1,6‐diynes and subsequent oxidative photocyclization. The scope of this novel two‐step process was demonstrated by the construction of diverse structures from substrates with various tethers and terminal aryl groups. Late‐stage
The Synthesis of Highly Substituted Cyclooctatetraene Scaffolds by Metal-Catalyzed [2+2+2+2] Cycloadditions: Studies on Regioselectivity, Dynamic Properties, and Metal Chelation
作者:Paul A. Wender、Justin P. Christy、Adam B. Lesser、Marc T. Gieseler
DOI:10.1002/anie.200903859
日期:2009.9.28
All‐kynes of COTs: A Ni0‐catalyzed [2+2+2+2] cycloaddition of 1,6‐diynes yields highly functionalized hexa‐ and octa‐substitutedcyclooctatetraenes (COTs; see picture) along with the first example of a fully intramolecular [2+2+2+2] cycloaddition product. The regioselectivity of this process is studied and the initial use of COT ligands is shown in the formation of a ZnII complex with a bis(oxazoline)
α,ω-diynes in the presence of [IrCl(cod)] 2 or [RhCl(cod)] 2 and DPPE gives cyclohexadiene derivatives which are readily aromatized with DDQ or MnO 2 . This two-step procedure gives access to highlysubstituted phthalimides in good yields.