Palladacycles ketones

Bis(pyrazolyl)borate copper complex 47 has been employed as a catalyst in the homogeneous and heterogeneous styrene epoxidation reactions <00JCS(CC)1653>. Pyrazole palladacycles 48 have proven to be stable and efficient catalysts for Heck vinylations of aryl iodides <00JCS(CC)2053>. An asymmetric borane reduction of ketones catalyzed by N-hydroxyalkyl-/-menthopyrazoles has been reported <00JHC983>. 

Pd(ll) catalysts can be employed as well. Compared to the standard Pd(ll) catalysts, the palladacycle catalyst 7 shows a broader compatibility with functional groups. Terminal alkynes, alkyl halides, and a-halogen ketones are tolerated <1997CB1449>. It is worth mentioning that other catalysts of Pd(ll) preferentially give dimerization products. 

The Pd(0) complexes [Pd(PPh3)4] and [Pd P(OPh)3 4] also react with hexafluoroacetone to give compounds containing a three-membered ring. With [Pd P(OMe)3 4] or [Pd P(OMe)2Ph 4], however, coupling of two ketones occurs to generate a five-membered palladacycle - ... 

Heterocyclic analogues of BINAP, such a< 2,2, 5,5 -tetramethyl-4,4 -bis(dipheny Iphosph and tested in the Heck reaction. Incorporaut sulfinyl group to a double bond elicits enj intramolecular Heck reaction. Optically ai ides are produced from (/ )-l-f-butylsulfinylcy Palladacycle (109) and its analogues ind rearrangement of allylic imidates. - For a thioamides, it is convenient to allylate thi dine. This process involves a thio-Claisen n Enantioselective deprotonation of ketones slum bis[yV-benzyl-N-(a-phenethyl)]amide.-- tonation of enolates. ... 

Aromatic ketones are akso accessible by coupling of ArB(OH)2 with thioesters RC0S(CH2)4X. Palladacycle 5 and Nal are present in the reaction milieu. 

The utilization of allylic alcohols as terminating agents of the palladacycle reaction sequence offered new access to a class of ketones or aldehydes containing the selectively substituted biphenyl unit. An example of the reaction is given by Eq. 44 (93% yield) [51]. 

Phenylhydrazones exhibit another mode of reaction (Scheme 65). The reaction of butadiene with the phenylhydrazone of acetaldehyde 204 (1 mol % (Ph3P)4Pd, THF, 110 °C, 24 h) affords a 2 1 mixture of 205 and 206 (86%). A small amount of the protic (H—Y) trapping prodnct was also observed. The formation of 205 can be rationalized by addition of the phenylhydrazone in the fashion of a R (R )C=Y-type electrophile to a palladacycle in an Sgs fashion to 208 followed by hydride transfer to 209. Rednctive elimination conld acconnt for the formation of 205. Thns, 206 could be formed via a similar pathway, by addition of the phenylhydrazone in an rather than fashion. The proposed hydride transfer invoked to rationalize the formation of the observed products offers interesting possibilities and appears worthy of further investigation. Phenylhydrazones derived from propanal, acetone, and methyl ethyl ketone behave similarly (60-95% yield), although the ratio of 205/206 and the proportion of the protic (H—Y-type) trapping product vary. 

Palladation of the ketone function of j ,j -dimethylhydrazonesr rearrangement of palladacycles derived from 2-oxopropionaldehyde phenylhydrazones, " orthopalladation of acetophenonephenylhydrazone, " and cyclopalla-dated compounds derived from pinacolone-j ,iV-dimethylhydrazone were reported. " ... 

Evidence has been obtained for palladacycles being catalyst precursors for soluble Pd(0) species and/or Pd nanoparticles.Palladacyles have been successfully employed as catalysts for alternating CO/alkene copo-lymerization. They have been amenable to allylic substitution,to oxygenation of unactivated sp C-H bonds,to allylic imidate rearrangement," " " " and to oxidation of alcohols to aldehydes and ketones." " ... 

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