Rhodium-Catalyzed Asymmetric [2 + 2 + 2] Cycloaddition of Unsymmetrical α,ω-Diynes with Acenaphthylene
作者:Yukimasa Aida、Yu Shibata、Ken Tanaka
DOI:10.1021/acs.joc.7b03042
日期:2018.3.2
It has been established that a cationic rhodium(I)/(R)-BINAP complex catalyzes the asymmetric [2 + 2 + 2] cycloaddition of unsymmetrical α,ω-diynes with acenaphthylene at room temperature to give the corresponding chiral multicyclic compounds with high yields and ee values. Interestingly, enantioselectivity highly depended on the structures of α,ω-diynes used. The structural requirements of α,ω-diynes
Facile Synthesis of Dibenzotetracenedione Derivatives by Rhodium‐Catalyzed [2+2+2] Cycloaddition/Spontaneous Aromatization
作者:Yukimasa Aida、Yu Shibata、Ken Tanaka
DOI:10.1002/asia.201801670
日期:2019.5.15
It has been established that a cationicrhodium(I)/SEGPHOS complex catalyzes the [2+2+2] cycloaddition of biphenyl‐linked 1,7‐diynes with 1,4‐naphthoquinone and anthracene‐1,4‐dione. Conveniently, spontaneous aromatization proceeded upon removal of the rhodium complex by passing the reaction mixture through an alumina column, to give the corresponding dibenzotetracenediones and dibenzopentacenediones
zirconacyclopentadienes (ZrPAHs). The efficiency of this process is demonstrated by a high‐yielding fivefold intramolecular coupling to form a helical ZrPAH with 16 fusedrings (from a precursor with no fusedrings). Several other PAH topologies are also reported. Protodemetalation of the ZrPAHs allowed full characterization (including by X‐ray crystallography) of PAHs containing one or more appended dienes with the
The enantioselective synthesis of polycyclic aromatic hydrocarbon (PAH)‐based planar chiralcyclophanes was achieved for the first time by the rhodium‐catalyzed intramolecular regio‐ and enantioselective [2+2+2] cycloaddition of tethered diyne‐benzofulvenes followed by stepwise oxidative transformations. The thus synthesized planar chiral bent cyclophanes, that possess bent p‐terphenyl‐ and 9‐fluorenone‐cores
[GRAPHICS]The new approach provides nonphotochemical syntheses of helicenes based on the easy, convergent, and modular assembly of key biphenylyl-naphthalenes and their platinum-catalyzed double cycloisomerization. This sequence of reactions provides a synthetic route to helicenes in two steps from simply accessible building blocks. Furthermore, the method enables the introduction of substituents into the hexahelicene skeleton. The strategy developed is exemplified by the synthesis of 6,10-dimethylhexahelicene and 1-methoxy-6,10-dimethylhexahelicene.