First Heck reaction with arenediazonium cations with recovery of Pd-triolefinic macrocyclic catalyst

The air- and moisture-stable phosphine-free palladium(0) complex 1 is a highly active and recoverable catalyst for Heck olefination of aryl diazonium tetrafluoroborates. The reactions were performed under aerobic conditions at room temperature to give the coupling products in excellent yields. [reaction: see text]     

Palladium catalyzed Heck reaction of arenediazonium tetrafluoroborate salts with Baylis-Hillman adducts: production of α-benzyl-β-keto esters

A novel experimental procedure to obtain α-benzyl-β-keto esters from the Heck reaction between arenediazonium tetrafluoroborate salts and Baylis-Hillman (BH) adducts in the presence of Pd(OAc)₂ as catalyst is described. The methodology is simple, straightforward and the use of arenediazonium salts as opposed to conventional arylhalides/triflates over the usual Heck reaction is highlighted.     

Synthesis of 2-substituted indoles via a palladium-catalyzed domino Heck reaction and dealkylation

A palladium-catalyzed domino Heck reaction and dealkylation for the preparation of 2-substituted indoles is described. This novel transformation is based on an intramolecular Heck reaction followed by dealkylation.     

Synthesis of fused indoles by sequential palladium-catalyzed Heck reaction and N-heteroannulation

A route to 3,4-fused indoles via two consecutive palladium-catalyzed reactions; an intramolecular Heck reaction followed by a reductive N-heteroannulation is described. Using this route, a number of indoles have been prepared having a variety of ring sizes anchored to the 3- and 4-position of the indole nucleus. Furthermore, a number of functional groups, both carbon and heteroatom substituents can be introduced in (and on) the additional ring without any detrimental effects on the two reactions.     

Synthesis of indoles from pyridinium salts.

The reaction of 1,2,5,6-tetramethyl-3-nitropyridinium perchlorate with acetone and piperidine on a solid carrier has given the novel, relatively stable 3-nitropyridine anhydro-base, 1,2,5-trimethyl-3-nitro-6-methylene-1,6-dihydropyridine, which bears alkyl groups only. This anhydro-base has been shown not to be an intermediate in the synthesis of indoles from 3-nitropyridinium salts.See [1] for Communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1214–1216, September, 1990.     

Synthesis of indoles from pyridinium salts 5. Secondary amines in the reaction of 3-nitropyridinium salts with acetone

The use of secondary amines in the reaction of 3-nitropyridinium salts with acetone makes it possible to isolate stable intermediates in the formation of indoles — (o-N,N-dialkylaminobenzyl)ketones — and to observe new reaction pathways — the formation of bisindolylpropanes and p-nitroanilines.See [1] for Communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1213–1221, September, 1988.     

Homolytic aromatic acetylation. A new substitution reaction of arenediazonium salts

The homolytic decomposition of arenediazonim salts induced by thermal, photochemical or redox (iron(II) salts or copper) sources in the presence of biacetyl gives substituted acetophenones with complete positional selectivity by a free-radical chain or a redox process.     

Hiyama cross-coupling of arenediazonium salts under mild reaction conditions

Palladium acetate [Pd(OAc)(2)]-catalyzed Hiyama cross-coupling of arenediazonium salts with organosilanes was found to generate biaryl products in high yields in alcoholic solutions. The simple and efficient protocol does not require any bases, ligands, or air/moisture. The transformation can tolerate either electron-donating or electron-withdrawing functional groups. Theoretical studies show that the transmetalation is the rate-limiting step for the cross-coupling reaction and both acetate and tetrafluoroborate anions may be involved in the direct reaction with the silicon atom.     

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.     

Synthesis of indoles from pyridinium salts

The detailed analysis of the products of the interaction of nitropyridinium salts with ketones and alkylamines resulted in new data testifying in favor of the previously proposed scheme for the formation of indoles from pyridinium salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 488–496, April, 1987.     

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.     

Synthesis of indoles from pyridinium salts. 4. Ketimines in the synthesis of indoles from 3-nitropyridinium salts

The possibility of using certain ketimines in place of mixtures of ketone and amine in the synthesis of indoles from 3-nitropyridinium salts has been demonstrated. The use of ketimines leads, in many cases, to increased yields of indoles and simplifies their isolation. It has been established that the rate of indole formation is considerably increased in polar aprotic solvents.For Communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1625–1628, December, 1987.     

Synthesis of indoles from pyridinium salts. 7. Sterically hindered alkyl-3-nitropyridinium salts in the synthesis of indoles

The introduction of bulky alkyl substituents (iso-Pr,tert-Bu) into any positions of the starting 3-nitropyridinium salt only increases the reaction time and decreases the yields of the corresponding alkylindoles somewhat.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 805–810, June, 1989.     

Palladium-catalyzed hydroarylation of alkynes with arenediazonium salts

The palladium-catalyzed hydroarylation of arenediazonium tetrafluoroborates with alkynes in the presence of triphenylsilane affords stereoselectively hydroarylation products in moderate to high yields. The reaction tolerates a variety of substituents including keto, ester, cyano, and nitro groups and can be performed as a one-pot procedure generating the arenediazonium salt in situ. With ethyl phenylpropynoate as the starting alkyne, the hydroarylation affords ethyl (Z)-2-arylcinnamates stereo- and regioselectively.     

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.     

Arylation of monothiobarbituric acid with arenediazonium salts

The first product under the conditions of O,S-arylation of monothiobarbituric acid is 5-aryl-hydrazonomonothiobarbituric acid. S-arylation then occurs to form the S-aryl ester of 5-arylhydrazonomonothiobarbituric acid. Further arylation leads to the O,S-diaryl esters of 5-arylhydrazonomonothiobarbituric acid. These esters are hydrolyzed under the influence of acids, alkalis, or hydrazine hydrate to thiophenols and phenols.We thank P.S. Pel'kis for his attention and interest in this research.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1271–1275, September, 1971.     

Substrate-directable Heck reactions with arenediazonium salts. The regio- and stereoselective arylation of allylamine derivatives and applications in the synthesis of naftifine and abamines

The palladium-catalyzed, substrate-directable Heck-Matsuda reaction of allylamine derivatives with arenediazonium salts is reported. The reaction proceeds under mild conditions, with excellent regio- and stereochemical control as a function of coordinating groups present in the allylamine substrate. The distance between the olefin moiety and the carbonylic system seems to play a key role regarding the regiocontrol. The method presents itself as robust, as simple to carry out, and with wide synthetic scope concerning the allylic substrates and the type of arenediazonium employed. The synthetic potential of the method is illustrated by the short total syntheses of the bioactive compounds naftifine, abamine, and abamine SG.     

Base-free Pd-MOF catalyzed the Suzuki-Miyaura cross-coupling reaction of arenediazonium tetrafluoroborate salts with arylboronic acids

A convenient and environmental benign synthesis of biaryls has been demonstrated by a straightforward reaction catalyzed by the palladium-containing metal-organic framework (Pd-MOF) [Pd (2-pymo)₂]_n (2-pymo = 2-pyrimidinolate). A series of functionalized biaryl derivatives have been synthesized in good to excellent yields by the Suzuki-miyaura cross-couplings of sustainable arenediazonium salts with a variety of arylboronic acids and the reactions were catalyzed by the Pd-MOF using methanol as a benign solvent. Those base- and additive-free catalytic reactions proceeded smoothly under non-anhydrous and non-degassed condition. Such transformation avoided high reaction temperature, tolerated many functional groups and presented a wide substrate scope. The catalyst could be recovered by filtration and reused for four successive cycles before collapse of the MOF structure.