Organopalladium compounds catalysts

The Suzuki reaction is the first of two reactions that utilize a palladium catalyst and proceed by way of an intermediate organopalladium compound. The second is the Heck reaction (Section 26.3). 

The oxidation of olefins to carbonyl compounds by means of palladium chloride catalysts (and involving intermediate organopalladium compounds) 22, 225, 226),... 

Organopalladium compounds prepared as discussed in this section can also serve as catalysts or catalyst precursors. Further investigations along this line will undoubtedly broaden the scope and applicability of the Pd catalysis in organic synthesis. 

In the next two sections, we ll describe some synthetic applications of organocopper and organopalladium compounds used to form C—C bonds between organic groups. The two types differ in that the organocopper compounds to be described are reagents present in stoichiometric amounts, whereas the organopalladium compounds are catalysts. 

The or//io-palladation of 3,4-dioxygenated benzylic tertiary amines by lithium tetrachloropalladate can be directed exclusively to either C-2 or C-6. Substitution at C-6 prevails when AcO, methylenedioxy, PhCH20, methoxymethyl ether, or HO substituents are attached to C-3, whereas palladation occurs exclusively at C-2 when C-3 bears methylthiomethyl ether or phenylthiomethyl ether substituents. The resulting organopalladium compounds are crystalline solids, stable to air and moisture, and can readily be carbonylated, alkylated, arylated, Kinetic studies of the acetoxylation of arenes by potassium peroxydisulphate and acetic acid in the presence of (2,2 -bipyridyl)palladium(ii) acetate catalyst have led to a revision of the mechanism. The reaction is now thought to proceed via... 

The Heck reaction consists in the Pd(0)-catalysed coupling of alkenes with an aryl or alkenyl halide or triflate in the presence of a base to form a substituted alkene (Scheme 7.1). The reaction is performed in the presence of an organopalladium catalyst. The halide or triflate is an aryl or a vinyl compound and the alkene contains at least one proton. 

Over the past 30 0 years, organopalladium chemistry has found widespread use in organic synthesis, and has been described in detail in a number of useful and informative books [1]. Palladium catalysts facilitate unique transformations that carmot be readily achieved using classical techniques, and in many cases palladium-catalyzed reactions proceed under mild reaction conditions and tolerate a broad array of functional groups. As such, the use of palladium catalysts for the synthesis of important, biologically active heterocyclic compounds has been the focus of a considerable amount of research [2],... 

A novel de novo synthesis of nucleosides (Scheme 1) involves the conversion of the mwo-compound 1, derived from furan, into the pure enantiomer 2 by two successive allylations using organopalladium intermediates. The first reaction uses 6-chloropurine as nucleophile, in the presence of a chiral bisphosphine. The subsequent elaboration of 2 indicates the use of the substituted malonate as an ingenious CO2H synthon. Use of the enantiomeric catalyst in the first step gives the D-nucleoside. ... 

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