PdCl2 reaction with

Isocoumarins.2 Isocoumarins can be prepared from benzoic acids by ortho-thal-lation followed by olefination promoted by PdCl2. Reaction with simple alkenes requires 1 equiv. of PdCl2 and a base-catalyzed reaction to effect the final cyclization. The reaction with vinyl halides or acetates generates isocoumarins directly and requires only catalytic amounts of PdCl2. 

C3H,)C2H3]PdCl2 Reaction with nucleophiles S.8.2.5.2 (CgH32)PdCl2... 

CeHg)C02CH3]PdCl2 Reaction with nucleophiles 5.8.2.5.2 Cj H CljPd... 

The most characteristic feature of the Pd—C bonds in these intermediates of both the stoichiometric and catalytic reactions is their reaction with nucleophiles, and Pd(0) is generated by accepting two electrons from the nucleophiles as exemplified for the first time by the reactions of 7r-allylpalladium chloride[2] or PdCl2-COD[3] complex with malonate and acetoacetate. It should be noted... 

Oxidative Reactions with Pd(II) Compounds PdCl2, CUCI2... 

Reaction of [Pd(acac)(r -allyl)] (allyl = C3H5, C4H7) with [PdCl2(Hpz)2] provides the homotrinuclear complexes [(/ -allyl)Pd(/LA-Cl)(/LA-pz)Pd(/A-Cl)(/LA-pz) Pd(r -allyl)] (79CJC3237). Further reaction with pyrazolate anion yields [(r -allyl)Pd(/A-pz)2Pd(/x,-pz)2Pd(r -allyl)]. 

Unlike the case of the Ni-catalyzed reaction, which afforded the branched thioester (Eq. 7.1), the PdCl2(PPh3)3/SnCl2-catalyzed reaction with 1-alkyne and 1-alkene predominantly provided terminal thioester 6 in up to 61% yield in preference to 7. In 1983, a similar hydrothiocarboxylation of an alkene was also documented by using a Pd(OAc)2/P( -Pr)3 catalyst system with t-BuSH to form 8 in up to 79% yield (Eq. 7.6) [16]. It was mentioned in the patent that the Pt-complex also possessed catalyhc activity for the transformation, although the yield of product was unsatisfactory. In 1984, the hydrothiocarboxylation of a 1,3-diene catalyzed by Co2(CO)g in pyridine was also reported in a patent [17]. In 1986, Alper et al. reported that a similar transformation to the one shown in Eq. (7.3) can be realized under much milder reaction conditions in the presence of a 1,3-diene [18], and the carboxylic ester 10 was produced using an aqueous alcohol as solvent (Eq. 7.7) [19]. 

Further investigations using model compounds showed that the formation of PdCl2 by a reaction with the solvent, as suggested by Brinkmann el al. [30], was also not responsible for the observed rapid deactivation. Palladium leaching after formation of Pd(0) was also excluded by experiments. The authors concluded therefore that the presence of allyl acetate facilitated the decomposition. 

A second type of organopalladium intermediates are 7r-allyl complexes. These complexes can be obtained from Pd(II) salts and allylic acetates and other compounds with potential leaving groups in an allylic position.79 The same type of 7i-allyl complexes can be prepared from alkenes by reaction with PdCl2 or Pd(02CCF3)2.80 The reaction occurs by electrophilic attack on the n electrons followed by loss of a proton. The proton loss probably proceeds via an unstable species in which the hydrogen is bound to... 

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