- PtIV-catalyzed cyclization of arene-alkyne substrates via intramolecular electrophilic hydroarylation
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(Figure presented) We herein report that PtCl4 has proven to be a hydroarylation catalyst with an efficiency and substrate scope superior to previously known methods. This catalyst demonstrated consistent performance with arene-yne substrates of diverse structural features, including propargyl ethers, propargylamines, and alkynoate esters, providing good to excellent yields of the 6-endo products (chromenes, dihydroquinolines, and coumarins). In contrast, Pt(II), Pd(II), and Ga(III) salts were shown to be sensitive to the substitution on the alkyne moiety.
- Pastine, Stefan J.,Youn, So Won,Sames, Dalibor
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p. 1055 - 1058
(2007/10/03)
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- Chromium-Templated Synthesis of Densely Substituted Distorted Arenes - Intramolecular Benzannulation of [(Alkynylaryl)alkenyl]carbene Complexes to Planar-Chiral Hydroquinoid [2.2]Heterametacyclophanes
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{[(meta-Alkynylphenyl)alkenyl]carbene}chromium compounds 1 and 2 have been synthesized by four-step (or five-step) and seven-step sequences, starting from 3-halophenol or 3-haloaniline, respectively. This approach, involving high-yielding Takai reactions and lithium cuprate additions, provides a novel and straightforward route to [(alkynylaryl)alkenyl](methoxy)carbene complexes. Upon gentle warming in tetrahydrofuran, (carbene)chromium compounds of this type undergo intramolecular benzannulation to give novel [2.2]heterametacyclophanes 21 and 22, bearing two chiral planes arising from the unsymmetrical substitution patterns both of the cyclophane skeleton and of the newly formed, Cr(CO)3-coordinated benzohydroquinone deck.
- Doetz, K. H.,Mittenzwey, S.
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