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Synthesis of Fluorenes via the Palladium‐Catalyzed 5‐ exo‐dig Annulation of o ‐Alkynylbiaryls
Author(s) -
Chernyak Natalia,
Gevorgyan Vladimir
Publication year - 2009
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200800765
Subject(s) - chemistry , annulation , intramolecular force , palladium , catalysis , dig , intermolecular force , benzene , cascade , stereochemistry , stereoselectivity , medicinal chemistry , combinatorial chemistry , molecule , organic chemistry , computer security , computer science , chromatography
The direct palladium‐catalyzed intramolecular hydroarylation of o ‐alkynylbiaryls proceeded in a highly stereoselective manner producing fluorenes 2 , the products of 5‐ exo‐dig cyclization, in excellent yields. The cascade intermolecular arylation, incorporated in this transformation, allowed for the efficient synthesis of fully substituted fluorenes 12 . These cyclizations proceed more rapidly with electron‐deficient benzene rings which, in combination with a substantial isotope effect observed, strongly supports a CH activation mechanism for the key annulation step.