Zirconium-Mediated Intramolecular Coupling of Terminal Alkynes and Their Subsequent Carbonylation: Novel Synthesis of Seven- and Eight-Membered Heterocycles
摘要:
AbstractThe development of a new method for the intramolecular coupling of terminal alkynes and for the synthesis of seven‐ and eight‐membered benzoheterocycles is reported. The key steps involve the generation of zirconocene‐alkyne complexes from 2‐bromoalkenes and the subsequent intramolecular carbometalation of olefins or acetylides. The 8‐unsubstituted zirconabicyclopentenes were carbonylated to afford unexpected products and allow access to polyfunctionalized molecules from simple starting materials.
作者:Theo D. Michels、Matthew S. Dowling、Christopher D. Vanderwal
DOI:10.1002/anie.201203147
日期:2012.7.23
In a short synthesis of echinopineB, a guaiane‐like intermediate was generated through a methylenecyclopentane annulation onto a substituted cycloheptenone. The resulting bicyclic compound was converted into the natural product by a PtCl2‐catalyzed enyne cycloisomerization (see scheme). Several late‐stage polycyclic rearrangement products were isolated and characterized.
Nickel-Catalyzed Enantioselective Pyridone C–H Functionalizations Enabled by a Bulky <i>N-</i>Heterocyclic Carbene Ligand
作者:Johannes Diesel、Anastasiia M. Finogenova、Nicolai Cramer
DOI:10.1021/jacs.8b01181
日期:2018.4.4
Annulated pyridones are an important scaffold found in many biologically active compounds. A Ni(0)-catalyzed C-H functionalization of 2- and 4-pyridones is disclosed, providing access to annulated pyridones via enantioselective intramolecular olefin hydroarylation. Key to the success of the transformation was the development of a sterically hindered and tunable N-heterocyclic carbene ligand resembling a chiral version of IPr. This ligand allows for mild reaction temperatures, and leads to the annulated pyridones in excellent yields and enantioselectivities.
The cis-hydrindan derivative 14b has been synthesized in up to 86% ee by an asymmetric Heck reaction starting with the prochiral alkenyl iodide 9b or the alkenyl triflate 13.
Zirconium-Mediated Intramolecular Coupling of Terminal Alkynes and Their Subsequent Carbonylation: Novel Synthesis of Seven- and Eight-Membered Heterocycles
作者:José Barluenga、Roberto Sanz、Francisco J. Fañanás
DOI:10.1002/chem.19970030820
日期:1997.8
AbstractThe development of a new method for the intramolecular coupling of terminal alkynes and for the synthesis of seven‐ and eight‐membered benzoheterocycles is reported. The key steps involve the generation of zirconocene‐alkyne complexes from 2‐bromoalkenes and the subsequent intramolecular carbometalation of olefins or acetylides. The 8‐unsubstituted zirconabicyclopentenes were carbonylated to afford unexpected products and allow access to polyfunctionalized molecules from simple starting materials.
Synthesis of Medium-Ring Nitrogen Heterocycles via Palladium-Catalyzed Heteroannulation of 1,2-Dienes
作者:Richard C. Larock、Chi Tu、Paola Pace
DOI:10.1021/jo980516p
日期:1998.10.1
nitrogen heterocycles are readily prepared by the palladium-catalyzed heteroannulation of a variety of 1,2-dienes by a range of tosylamide- and amine-containing aryl and vinylic halides. The ease of ring formation is seven > eight > nine, and better results are obtained using aryl halides, rather than vinylic halides, and tosylamide functionality, rather than amine functionality. The reaction is suggested