The palladium-catalyzed Heck arylation of olefins with arenediazonium salts as a sustainable strategy in organic synthesis

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Heck arylation of styrenes with arenediazonium salts: short, efficient, and stereoselective synthesis of resveratrol, DMU-212, and analogues

Short, efficient, and stereoselective synthesis of the trans-stilbenes resveratrol, DMU-212, and analogues of both compounds are described. The synthesis of these important anti-cancer agents feature the palladium catalyzed Heck-Matsuda arylation of styrenes with arenediazonium tetrafluoroborates.     

The scope of the Heck arylation of enol ethers with arenediazonium salts: a new approach to the synthesis of flavonoids

The scope of the Heck arylation of cyclic and acyclic enol ethers with arenediazonium salts was evaluated. Arylation of 2,3-dihydrofuran yielded 2-aryl-2,5-dihydrofurans as the major adducts (>99:1) except when using n-Bu₄NHSO₄ as additive or 4-NO₂PhN₂BF₄ as arenediazonium salt. 2,3-Dihydropyran provided mixtures of the three possible isomeric Heck adducts. Arylation of n-butylvinylether with arenediazonium bearing electron-donating groups resulted in substituted acetophenones as almost exclusive products in good overall yields. Substituted 4H-chromenes provided 2-aryl-2H-chromenes in moderate yield when applying the Pd(OAc)₂/2,6-di-t-butyl-4-methylpyridine catalytic system, which were applied in the synthesis of flavonoids.     

The Heck-type arylation of allylic alcohols with arenediazonium salts

The Heck coupling of ArN₂BF₄ with secondary allylic alcohols, carried out in methanol using Pd(dba)₂ as catalyst without extra ligands and base, leads to the corresponding β-arylated carbonyl compounds. Such conditions afford arylated acetals from primary allylic alcohols.     

Regio- and stereoselective Heck arylations of N-carbomethoxy-L- 3-dehydroproline methyl ester with arenediazonium salts. Total synthesis of neuroexcitatory aryl kainoids

The Heck arylation of N-carbomethoxy-L-3-dehydroproline methyl ester with arenediazonium tetrafluoroborates produced chiral 4-aryldehydroproline derivatives in moderate to good yields in a highly regio- and stereocontrolled fashion. A rationale for the unexpected high regioselectivity is provided using Deeth's model. Heck adduct 15 (G = o-CH3O) was converted into several aryl kainoids using concise and efficient routes.     

Highly regio- and stereoselective synthesis of tricyclic frameworks using Baylis-Hillman derivatives

A simple and convenient synthetic route for the synthesis of tricyclic chromeno[4,3-b]pyrrolidine frameworks using Baylis-Hillman bromides involving in situ formation of an imine, decarboxylation and a [3+2] cycloaddition sequence is described.     

Highly regio- and stereoselective synthesis of indene derivatives via electrophilic cyclization

[reaction: see text] Indene or naphthalene derivatives are readily prepared in moderate to excellent yields with high regio- and stereoselectivity under very mild reaction conditions by the reaction of acetylenic malonates and ketones with I2, ICl, or NIS. The resulting iodides can be further elaborated using palladium-catalyzed coupling reactions.     

Pd-catalyzed arylation reactions with phenol diazonium salts: application in the synthesis of diarylheptanoids

The first total synthesis of the natural product (3S,7R)-5,6-dehydro-de-O-methyl centrolobine and various analogues is reported, using a highly regio- and diastereoselective Mizoroki-Heck reaction of phenol diazonium salts and enantiopure dihydropyrans. The assigned relative configuration was confirmed by single-crystal X-ray structure analysis, but a revision of the absolute configuration is proposed based on polarimetric measurement.     

Heck reaction of arenediazonium salts with N,N-diprotected allylamines. Synthesis of cinnamylamines and indoles

Novel palladium-catalyzed reactions of arenediazonium tetrafluoroborates with N,N-diprotected allylamines are presented. The reaction of arenediazonium tetrafluoroborates with N,N-(Boc)(2) allylamine allows for an easy approach to cinnamylamines whereas using 2-alkynyl-N-(allyl)trifluoroacetanilides and 2-iodo-N-(allyl)trifluoroacetanilide the reaction provides a useful tool for appending indole rings to aniline fragments.     

Two-step regio- and stereoselective synthesis of cis-vinylstannanes

Herein we describe a novel stereoselective synthesis of cis-vinylstannanes employing the widely established Li/Te exchange pathway. In contrast to previously reported methods of cis-selective hydrostannation (i.e., ZrCl4), this method demonstrates compatibility toward oxygenated substrates.     

Heck arylation of endocyclic enecarbamates with diazonium salts. Improvements and a concise enantioselective synthesis of (-)-codonopsinine

Total enantioselective synthesis of the natural (-)-codonopsinine was accomplished in seven steps with an overall yield of approximately 16% starting from the five-membered endocyclic enecarbamate 4. The total synthesis features a highly efficient and stereoselective Heck arylation of endocyclic enecarbamate 4 with p-methoxybenzenediazonium tetrafluoroborate and a stereoselective epoxidation/epoxide opening sequence as key steps.     

Pd-catalyzed cross-coupling reactions of arenediazonium salts with arylsilanes and aryltrifluoroborates in water

Pd-catalyzed cross-coupling reactions of various arenediazonium salts with ArSi(OR)₃ and KArBF₃ have been achieved in good to excellent yields under simple aerobic conditions in water at room temperature. The functional group tolerance makes these transformations as attractive alternatives to the traditional cross-coupling approaches. Furthermore, the sequence can also be performed in a one-pot domino process, omitting the isolation of the intermediate arenediazonium salt.     

Reaction of arenediazonium salts with rhodanine,thiohydantoin, and their derivatives

Under conditions of the O,S-arylation of rhodanine and isorhodanine by arenediazonium salts, 5-arylhydrazono-2-arylthio-2-thiazolin-4-ones and 5-arylhydrazono-4-arylthio-3-thiazolin-2-ones have been obtained. Under similar conditions, 5-ethylrhodanine forms not only 2-arylthio-5-ethyl-2-thiazolin-4-ones but also 2-arylazothio-5-ethyl-2-thiazolin-4-ones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1487–1492, November, 1973.     

Simple and catalyst-free method for the synthesis of diaryl selenides by reactions of arylselenols and arenediazonium salts

We describe here a simple and catalyst-free method to synthesize diaryl selenides by reaction of arenediazonium tetrafluoroborate salts with arylselenols, generated in situ by using diaryl diselenides and hypophosphorous acid (H₃PO₂), using THF as solvent. This is a direct nucleophilic aromatic substitution (SNAr) reaction performed with diaryl diselenides and arenediazonium salts bearing electron-withdrawing and electron-donating groups affording the corresponding diaryl selenides in moderated to good yields.     

Facile regio- and stereoselective carbon-carbon coupling of phenol derivatives with aryl aziridines

A chemo-, regio-, and stereoselective direct carbon-carbon coupling of readily available aryl borates with N-protected aryl aziridines provides a method for the synthesis of new 2-(o-hydroxyaryl)-2-aryl ethylamines which can be used, in a novel annulation sequence, to give stereodefined substituted 3-aryl indolines. [reaction: see text]     

Highly regio- and stereoselective one-pot synthesis of carbohydrate-based butyrolactones

The use of manganese(III) acetate allows the direct synthesis of diverse arrays of [4.3.0] bicyclic carbohydrate-based γ-lactone building blocks from glycals. A mechanism to explain the high regio- and stereoselectivity is proposed. The new reaction has the potential to generate libraries for biological screening.     

A regio- and stereoselective synthesis of 1,2-disubstituted vinylsilanes

The alkylcopper reagents prepared from RMgBr and CuBr react with trimethylsilylacetylene to give regio- and stereo-selectivity 1-trimethylsilyl-1(Z)-alkenylcopper adducts. Hydrolysis affords 1-trimethylsilyl-1(E)-alkenes exclusively. Alkylation, acylation, halogenation, and stannylation proceed stereoselectively to afford synthetically useful intermediates. Homopropargylation of alkyl 1-trimethylsilyl-1(Z)-alkenylcuprates provided better yield than that of the original vinylcopper reagents.     

cis-Carbocuperation of acetylenic sulfoxides and corresponding applications in the regio- and stereoselective synthesis of polysubstituted vinyl sulfoxides

cis-Carbocuperation reaction of monoorganocopper reagent with acetylenic sulfoxides, followed by electrophilic reaction with a variety of electrophiles, provided a regio- and stereoselective method to prepare the versatile polysubstituted vinyl sulfoxides. Sonogashira cross-coupling reaction of the obtained α-iodovinyl sulfoxides with terminal acetylenes was also investigated to afford the versatile conjugate sulfinyl enynes.