- Enantioselective Synthesis of Distorted π-Extended Chiral Triptycenes Consisting of Three Distinct Aromatic Rings by Rhodium-Catalyzed [2+2+2] Cycloaddition
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The enantioselective synthesis of distorted π-extended chiral triptycenes, consisting of three distinct aromatic rings, has been achieved with high ee value of 87 % by the cationic rhodium(I)/segphos complex-catalyzed enantioselective [2+2+2] cycloaddition of 2,2′-di(prop-1-yn-1-yl)-5,5′-bis(trifluoromethyl)-1,1′-biphenyl with 6-methoxy-1,2-dihydronaphthalene followed by the diastereoselective Diels–Alder reaction and aromatization. Demethoxy derivatives were also synthesized by the C?O bond cleavage. In this synthesis, the use of the electron-deficient diyne and the electron-rich alkene is crucial to suppress the undesired strain-relieving carbocation rearrangement and stabilize the distorted triptycene structure.
- Aida, Yukimasa,Shibata, Yu,Tanaka, Ken
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- Synthesis of N-fused tricyclic indoles by a tandem [1,2] stevens-type rearrangement/1,2-alkyl migration of metal-containing ammonium ylides
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(Chemical Equation Presented) An alkyne moiety is activated efficiently with a [W(CO)6] or [ReBr(CO)5] catalyst in the presence of an amine functionality in the title reaction of N-(2-alkynylphenyl)-amines. The resulting ammonium ylides undergo rearrangement to form a variety of N-fused polycyclic indole derivatives (see scheme; n = 1,2; R = alkyl, Ph).
- Takaya, Jun,Udagawa, Shuji,Kusama, Hiroyuki,Iwasawa, Nobuharu
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supporting information; experimental part
p. 4906 - 4909
(2009/02/08)
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- PtCl2-catalyzed hydrative cyclization of trialkyne functionalities to form bicyclic spiro ketones
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(Chemical Equation Presented) Triple rounds: A regioselective hydrative cyclization of triynes has been developed to give bicyclic β-hydroxy spiro ketones, which undergo subsequent dehydration to give the β,γ- unsaturated ketones (see scheme). Model reactions suggest that this platinum catalysis includes two selective hydrations, an alkyne insertion, and an aldol condensation.
- Chang, Hsu-Kai,Datta, Swarup,Das, Arindam,Odedra, Arjan,Liu, Rai-Shung
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p. 4744 - 4747
(2008/02/08)
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