A novel copper-catalyzed one-pot trifluoromethylation/aryl migration/desulfonylation and C(sp(2))-N bond formation with conjugated tosyl amides as starting materials is presented here. The reaction affords α-aryl-β-trifluoromethyl amides bearing a quaternary stereocenter or trifluoromethylated oxindoles in a regioselective manner.
The enantioselective synthesis of molecules containing quaternary stereocenters is a field of intense research interest and development. Among the known organic transformations, carbopalladation-initiated domino transformations constitutes a general method for the construction of compounds containing cyclic or spiro quaternary stereocenters. In this Minireview, recent achievements in palladium-catalyzed domino Heck/C-H functionalizations and developments in enantioselective carbopalladation-initiated domino processes are summarized.
The addition of a variety of radicals to the double bond of N-(arylsulfonyl)acrylamides can trigger cyclization/aryl migration/desulfonylation cascades via amidyl radical intermediates 2. Herein, we demonstrate the synthetic utility of these intermediates in subsequent C-C and C-X bond-forming events to rapidly build up molecular complexity. First, we describe a regioselective one-pot synthesis of CF3-, SCF3-, Ph2(O)P-, and N3-containing indolo[2,1-a]isoquinolin-6(5H)-ones from N-[(2-ethynyl)arylsulfonyl]acrylamides through a multi-step radical reaction cascade. The process involves the one-pot formation of four new bonds (one C-X, two C-C, and one C-N), a formal 1,4-aryl migration, and desulfonylation of the starting material. Second, we present a one-pot synthesis of 3,3-disubstituted-2-dihydropyridinones from N-(arylsulfonyl)acrylamides and 1,3-dicarbonyl compounds. In this case, a silver-catalyzed radical cascade process involving the sequential formation of two new C-C bonds and one C-N bond, a formal 1,4-aryl migration, and desulfonylation of the starting material explains the regioselective formation of densely functionalized heterocycles in a straightforward manner. Control experiments have unraveled the key intermediates as well as the sequence of individual steps involved in these transformations.
A Ni-catalyzed enantioselective
reductive diarylation of activated
alkenes by domino cyclizative/cross-coupling of two aryl bromides
is developed. This reaction proceeds under very mild conditions and
shows broad substrate scope, without requiring the use of preformed
organometallic reagents. Moreover, this approach provides direct access
to various bis-heterocycles bearing all-carbon quaternary centers
in synthetically useful yields (up to 81%) with excellent enantioselectivity
(>30 examples, 90–99% ee).
Metal-free: The first metal-free aryltrifluoromethylation of activated alkenes has been developed. With this method, trifluoromethylated isoquinolinediones, spirobicycles, oxindoles, and α-aryl-β-trifluoromethylamides were obtained with high control of the regioselectivity.
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