Intramolecular Aryl Migration of Diaryliodonium Salts: Access to ortho-Iodo Diaryl Ethers
By using vicinal trifluoromethanesulfonate-substituted diaryliodonium salts, a novel approach was developed for the synthesis of ortho-iodo diaryl ethers by intramolecular aryl migration. The reaction conditions are mild with a broad substrate scope. Mechanistic insight suggests a sulfonyl-directed nucleophilic aromatic substitution pathway. Additionally, the product ortho-iodo diaryl ethers serve as versatile synthons as demonstrated with several coupling reactions. Furthermore, a useful thyroxine analogue of the 3-iodo-l-thyronine (3-T1) derivative was synthesized by this aryl migration procedure.
Chen, Huangguan,Han, Jianwei,Wang, Limin
p. 12313 - 12317
(2018/09/10)
Four- and Sixfold Tandem-Domino Reactions Leading to Dimeric Tetrasubstituted Alkenes Suitable as Molecular Switches
A highly efficient palladium-catalyzed fourfold tandem-domino reaction consisting of two carbopalladation and two C-H-activation steps was developed for the synthesis of two types of tetrasubstituted alkenes 3 and 6 with intrinsic helical chirality starting from substrates 1 and 4, respectively. A sixfold tandem-domino reaction was also developed by including a Sonogashira reaction. 20 compounds with different substitution patterns were prepared with yields of up to 97%. Structure elucidation by X-ray crystallography confirmed helical chirality of the two alkene moieties. Photophysical investigations of some of the compounds showed pronounced switching properties through light-controlled changes of their stereochemical configuration.
Practical radical cyclizations with arylboronic acids and trifluoroborates
Practical radical cyclizations using organoboronic acids and trifluoroborates take place in water, open to air, and in a scalable fashion employing catalytic silver nitrate and stoichiometric potassium persulfate. Both Pschorr-type cyclizations and tandem radical cyclization/trap cascades are described, illustrating the utility of these mild conditions for the generation of polycyclic scaffolds.
Lockner, Jonathan W.,Dixon, Darryl D.,Risgaard, Rune,Baran, Phil S.
supporting information; experimental part
p. 5628 - 5631
(2011/12/03)
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