Palladium-Catalyzed Domino Reaction Research Articles

Enantioselective Palladium‐Catalyzed Total Synthesis of Vitamin E by Employing a Domino Wacker–Heck Reaction

An enantioselective total synthesis of vitamin E in which a novel palladium-catalyzed domino reaction was employed as the key step is described. This reaction allows the formation of the chiral chroman framework and the concurrent introduction of part of the side chain of vitamin E. The sequence comprises an enantioselective Wacker cyclization and a subsequent Heck reaction. Accordingly, reaction of alkenylphenol 12 with methyl vinyl ketone (13) in the presence of catalytic amounts of Pd(OTFA)(2) (TFA = trifluoroacetate), the enantiopure ligand (S,S)-Bn-BOXAX (8 b; Bn = benzyl, BOXAX = 2,2'-bis(oxazolyl)-1,1'-binaphthyl, and p-benzoquinone (9) as an oxidant gives access to chiral chroman 10 with an enantioselectivity of 97 % ee in 84 % yield. Chroman 10 is then converted into 24 by an aldol condensation reaction with (3R)-3,7-dimethyloctanal (11). Subsequent 1,2-addition of methyllithium, elimination of water, and hydrogenation yields vitamin E.

Understanding Sulfone Behavior in Palladium‐Catalyzed Domino Reactions with Aryl Iodides

Unlike traditionally used acyclic 1,2-disubstituted alkenes, the reaction of alpha,beta-unsaturated phenyl sulfones with aryl iodides under Heck reaction conditions takes place mainly by means of a four-component domino process, involving one unit of the alkene and three units of the aryl iodide, affording substituted 9-phenylsulfonyl-9,10-dihydrophenanthrenes. We report here the results of a computational study on the mechanism of this domino arylation reaction. Based on these results we can explain why vinyl sulfones, unlike other electron-deficient alkenes such as enones, preferentially follow this domino pathway instead of the usual Heck pathway. The key step is a C-H activation process in which a five-membered palladacycle is formed. The greater ability of vinyl sulfones, relative to enones, to reach the transition state that leads to the formation of the initial palladacycle makes the difference.

Palladium‐Catalyzed Alkylation—Hydride Reduction Sequence: Synthesis of meta‐Substituted Arenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Palladium-Catalyzed Alkylation−Hydride Reduction Sequence: Synthesis of Meta-Substituted Arenes

A new three-component, palladium-catalyzed domino reaction which gives access to meta-substituted arenes using aryl iodides and primary alkyl halides is reported. Various functional groups are tolerated on both the aryl iodide and alkyl halide. In addition, isotopic labeling studies provide insight into the mechanism of this Catellani-type reaction. [reaction: see text]

Stereoselective Synthesis of 3-Alkylideneoxindoles via Palladium-Catalyzed Domino Reactions

We have developed efficient catalytic methods for the stereoselective and diversity synthesis of various (E)-, (Z)-, and disubstituted 3-alkylideneoxindoles and 3-alkylidenebenzofuran-2-ones via palladium-catalyzed Heck/Suzuki-Miyaura, Heck/Heck, and Heck/carbonylation/Suzuki-Miyaura domino reactions.

The Virtue of Palladium-Catalyzed Domino Reactions − Diverse Oligocyclizations of Acyclic 2-Bromoenynes and 2-Bromoenediynes

The domino-type combination of consecutive palladium-catalyzed cross-coupling reactions with subsequent pericyclic transformations offers a very fast access to various oligocyclic skeletons. This Account highlights all-intramolecular, intra-intermolecular, and all-intermolecular organopalladation cascades leading to 1,3,5-hexatrienes, which undergo consecutive 6pi-electrocyclizations with closure of three, two, or just one ring, respectively. Sequences of cross-coupling reactions and Diels-Alder additions are also discussed, as well as tricyclizations of 2-bromoenediynes giving rise to bisannelated benzene and fulvene derivatives.

A Novel Palladium-Catalyzed Domino Tsuji−Trost−Heck Process for the Synthesis of Tetrahydroanthracenes

A novel type of palladium-catalyzed domino reaction is described combining Tsuji−Trost and Heck reactions. This method allows efficient access to tetrahydroanthracene derivatives 1 in up to 89% isolated yield in a one-pot process starting from the diketone 3. The tetrahydroanthracene structural motif is found in many natural products, such as in the antibiotic tetracycline.

Palladium-Catalyzed Domino Reaction of 4-Methoxycarbonyloxy-2-butyn-1-ols with Phenols: A Novel Synthetic Method for Cyclic Carbonates with Recycling of CO2

Palladium-Catalyzed Domino Reaction of 4-Methoxycarbonyloxy-2-butyn-1-ols with Phenols: A Novel Synthetic Method for Cyclic Carbonates with Recycling of CO2

Palladium-Catalyzed Domino Reaction of 4-Methoxycarbonyloxy-2-butyn-1-ols with Phenols: A Novel Synthetic Method for Cyclic Carbonates with Recycling of CO2

Erneut fixiert wird das CO2 aus einer Decarboxylierung bei der palladiumkatalysierten Dominoreaktion zwischen 4-Methoxycarbonyloxy-2-butin-1-olen und Phenolen. Auf diese Art lässt sich unter milden Bedingungen durch effizienten Wiedereinbau des CO2-Moleküls eine Vielzahl cyclischer Carbonate herstellen (Gleichung (1) zeigt ein Beispiel). Es handelt sich damit um ein praktisches und umweltfreundliches Verfahren.

Palladium-Catalyzed Domino Reaction of 4-Methoxycarbonyloxy-2-butyn-1-ols with Phenols: A Novel Synthetic Method for Cyclic Carbonates with Recycling of CO2

Palladium-Catalyzed Domino Reaction of 4-Methoxycarbonyloxy-2-butyn-1-ols with Phenols: A Novel Synthetic Method for Cyclic Carbonates with Recycling of CO2

Palladium-Catalyzed Domino Reaction of 4-Methoxycarbonyloxy-2-butyn-1-ols with Phenols: A Novel Synthetic Method for Cyclic Carbonates with Recycling of CO2.

Refixation of the CO2 from a decarboxylation occurs in the palladium-catalyzed domino reaction of 4-methoxycarbonyloxy-2-butyn-1-ols with phenols. The reaction enables the construction of various cyclic carbonates [Eq. (1)] by efficient reincorporation of the CO2 molecule under mild conditions, and is thus a convenient and environmentally friendly method.