- Remote Functionalization of α,β-Unsaturated Carbonyls by Multimetallic Sequential Catalysis
-
The remote functionalization of α,β-unsaturated carbonyls by an array of multimetallic sequential catalytic systems is described. The reactions are triggered by hydrometalation using [Pd-H] or [Ru-H] isomerization catalysts and driven by the formation of thermodynamically more stable 1,2-vinyl arenes. The Pd-catalyzed deconjugative isomerization was combined with a Cu-catalyzed β-borylation of the transiently generated styrenyl derivatives to deliver a range of products that would not be accessible with the use of a single catalyst. [Pd/Cu] catalytic systems were also identified for the highly enantioselective α-hydroboration and α-hydroamination of the styrenyl intermediates. Difunctionalization simultaneously at the benzylic and homobenzylic positions was achieved by combining the isomerization process with Sharpless asymmetric dihydroxylation (SAD) using [Pd/Os] or [Ru/Os] couples. Starting from a simple α,β-unsaturated ester, an isomerization/dihydroxylation/lactonization sequence gave access to a naturally occurring γ-butyrolactone in good yield, with excellent diastereo- and enantioselectivity.
- Romano, Ciro,Fiorito, Daniele,Mazet, Clément
-
p. 16983 - 16990
(2019/10/28)
-
- Catalytic olefin hydroamination with aminium radical cations: A photoredox method for direct C-N bond formation
-
While olefin amination with aminium radical cations is a classical method for C-N bond formation, catalytic variants that utilize simple 2° amine precursors remain largely undeveloped. Herein we report a new visible-light photoredox protocol for the intramolecular anti-Markovnikov hydroamination of aryl olefins that proceeds through catalytically generated aminium radical intermediates. Mechanistic studies are consistent with a process involving amine oxidation via electron transfer, turnover-limiting C-N bond formation, and a second electron transfer step to reduce a carbon-centered radical, rendering the overall process redox-neutral. A range of structurally diverse N-aryl heterocycles can be prepared in good to excellent yields under conditions significantly milder than those required by conventional aminium-based protocols.
- Musacchio, Andrew J.,Nguyen, Lucas Q.,Beard, G. Hudson,Knowles, Robert R.
-
supporting information
p. 12217 - 12220
(2014/12/09)
-
- PALLADIUM CATALYZED ALLYLATION OF REFORMATSKY REAGENTS. SYNTHESIS OF γ,δ-UNSATURATED ESTERS.
-
Reformatsky reagents regioselectively react under mild conditions with allylic acetates in the presence of Pd(PPh3)4 to give γ,δ-unsaturated esters in good yields.
- Boldrini, Gian Paolo,Mengoli, Marina,Tagliavini, Emilio,Trombini, Claudio,Umani-Ronchi, Achille
-
p. 4223 - 4226
(2007/10/02)
-
- Competitive - and -Sigmatropic Rearrangements
-
Several cases of the oxy-Cope rearrangement, which typically prefers the -sigmatropic route, are now known to occur in a -sigmatropic fashion.By contrast, the symmetry-allowed thermal rearrangement of carbanions (or their enol derivatives; e.g.,
- Arnold, Richard T.,Kulenovic, Srdanka T.
-
p. 891 - 894
(2007/10/02)
-