Organo-palladium

TL2403). Thus, or /io-cyclopalladation of acetanilide 138 gave organo-palladium reagent 139. The or /io-vinylation of 139 afforded enone 140, which was then cyclized to quinoline 141 under acidic conditions. Notice this reaction requires stoichiometric amounts of Pd(OAc)2. 

The conversion of ethylene to acetaldehyde using a soluble palladium complex, developed in the late 1950s, was one of the early applications of homogeneous catalysis and the first organo-palladium reaction practised on an industrial scale [40], Typically this reaction requires stoichiometric amounts of CuCl under aerobic conditions. The use of copper represents not only an environmental issue, but often limits the scope of ligands that can be used in conjunction with Pd. 

Tn most organic syntheses involving palladium, palladium-carbon sigma bonds are involved at some stage in the reaction pathway (J). Two important types of reactions which take place in organo-palladium syntheses are oxidative additions to palladium(O) and addition of palladium (II) complexes across olefins as well as the respective reverse (elimination) reactions. In both these reactions, carbon-palladium sigma bonds are made and broken ... 

S. Brase, J. Kobberling N. Griebenow, in Handbook of Organo-Palladium Chemistry (E.-i. Negishi, ed.), Chapter X. 3. Wiley, New York, 2002. 

Catellani, M. Handbook of Organo-palladium Chemistry for Organic Synthesis, Vol. 1 Negishi, E.-I., ed. ... 

Sonogashira K (2001) Sonogashira reaction. In Negishi E (ed) Handbook of organo-palladium chemistry for organic synthesis. Wiley-VCH, New York, in press/chap 3/ Sect 3.2.8.1... 

The mechanism for this palladium-catalyzed cross-coupling reaction comprises the initial oxidative addition of the electrophile 37 to the palladium(O) catalyst followed by transmetallation of triethylsilane to yield the corresponding bis(organo)palladium(II) complex 39, which then undergoes reductive elimination to form the alkene 40 and to regenerate the palladium(O) catalyst. 

Palladium-catalyzed arylation and vinylation of alkene is referred to as the Mizoroki-Heck reaction and is one of the most widely used Pd(0)-catalyzed C-C bond formations in organic synthesis. However, the reaction has not been extensively employed for C-glycosylation [96]. The example shown in O Scheme 67 outlines the reaction of iodopyridine and furanose gly-cal for the synthesis of C-nucleoside [97]. The mechanism began with the oxidative addition of iodopyridine to Pd(0) catalyst, and the resulting organo-palladium species was inserted by... 

When the carbanion nucleophile is not bound to the same metal center as the complexed olefin, then anti (or trans) addition may occur, as is foundin organo-palladium chemistry ... 

During the last 30 years, numerous books, monographs, and reviews have been published on organo-palladium chemistry and palladium-catalyzed reactions such as the Heck, Suzuki, Stille, and Sonogashira reactions [1-52], These represent well-established methods for carbon—carbon bond formation in organic synthesis. 

A more general solution to the problem is to change the nucleophile from an organo-lithium or copper species to an organo-palladium compound and this leads on to the Heck reaction. 

Trimethylpalladium(IV) complexes are highly unstable but structures have been assigned to organo-palladium(IV) complexes with flexible bidentate ligands such as (py)2CHMe. Conformational and fluxional effects have been reported and compared with related Me3Pt(IV) systems. 

This review provides a compilation of the most well-known catalytic reactions related to organo-palladium chemistry. The references have been covered up to November 1995. The mechanisms are generally described with respect to the data in the literature and by the use of information found mainly in publications. For each catalytic cycle, the chemical parameters are listed and one or more related references are given. As an example, for the cross-coupling reactions between RX and R M, the identity of R, R, X, and M parameters are defined. The references which are quoted contain at least one example of these parameters. A few palladium-catalyzed reactions are not reported in this review because of insufficient data concerning the mechanism or because the reaction affords a complex mixture of products. 

The role of the copper(ii) ions is to increase the activity of the organo-palladium species, possibly by withdrawal of electrons from the environment of the palladium(n). 

Reviews have appeared on the use of the Wittig reaction in industrial practice, the Claisen rearrangement, synthetic applications of the retro-Diels-Alder reaction, organo-palladium intermediates for the alkylation and arylation of olefins, the Prins reaction to give 1,3-dienes, and intramolecular [4 + 2] (Diels-Alder) and [3 + 2] cycloadditions.An interesting discussion of the regiospecificity of the Diels-Alder reaction in terms of frontier orbital overlap favours the Woodward-Katz concept. Useful alkyne and polyene coupling reactions are described in reviews on the chemistry of vitamin the synthesis of insect sex... 

The Heck reaction (Mizoroki-Heck reaction) is the reaction of an unsaturated halide (or triflate) with an alkene and a strong base and palladium catalyst to form a substituted alkene [41, 42]. The reaction is performed in the presence of an organo-palladium catalyst. The halide or triflate is an aryl, benzyl, or vinyl compound, and the alkene contains at least one proton and is often electron deficient, such as acrylate ester or an acrylonitrile. The catalyst can be tetrakis(triphenylphosphine)palladium... 

Erase, S. and de Meijere, A. (2002) Palladium-catalyzed tandem and cascade carbopalladation -termination with alkenes, arenes and related jr-compounds, mHandbook of Organo-Palladium Chemistry (ed. E.-i. Negishi), John WUey Sons Inc., New York, pp. 1369 05. 

The combination of a Mizoroki-Heck reaction with a C—H activation is a domino process that has been encountered with increasing frequency in the past few years. This type of transformation takes place if the organo-palladium intermediate does not react in the usual way but activates an aryl- or vinyl-H bond in close vicinity, forming a new palladium(II) species that can react further with electrophiles or nucleophiles and giving rise to the formation of another C—C or C-Tieteroatom bond. 

The reactions occurred well even at room temperature, but the impracticality of using stoichiometric amounts of palladium severely limited the use. Subsequently, we overcame this problem by forming the organo-palladium salts by the reaction of aryl iodides directly with finely divided palladium, a reaction which Mizoroki discovered independently at about the same time. 

Organo-palladium compounds of the type (43) containing an q -polysubstituted butadienyl group were used as precursors in the selective syntheses of various carbocyclic and heterocyclic... 

Trost and his co-workers continue to develop new synthetic methods, such as the cyclization of (144) to (145), " which are based on the chemistry of organo-palladium compounds. The 1,3-dipolar addition of a nitrone to an olefinic double bond yields an oxazoline, but if the reaction is intramolecular it can provide an excellent method for the synthesis of carbocycles. For example, the conversion of (146) into (147) is a key step in a new Synthesis of a-bisabolol (148). ... 

Heck, R. F. Mechanism of Arylation and Carbomethoxylation of Olefins with Organo-palladium Compounds. J Am Chem Soc 91, 6707-6714 (1969). 

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