Allylic esters palladium® chloride

Synthesis of isomeric chiral protected (63 )-6-amino-hexahydro-2,7-dioxopyrazolo[l,2- ]pyrazole-l-carboxylic acid 280 is shown in Scheme 36. Crude vinyl phosphonate 275, obtained by treatment of diethyl allyloxycarbonylmethyl-phosphonate with acetic anhydride and tetramethyl diaminomethane as a formaldehyde equivalent, was used in the Michael addition to chiral 4-(f-butoxycarbonylamino)pyrazolidin-3-one 272. The Michael addition is run in dichloro-methane followed by addition of f-butyl oxalyl chloride and 2 equiv of Huning s base in the same pot to provide 276 in 58% yield. The allyl ester is deprotected using palladium catalysis to give the corresponding acid 277, which is... 

Allyl esters and allyl chlorides have been widely used as substrates for catalytic allylic animation. As shown in Table 1, the nature of the leaving group X and the choice of the palladium(O) catalyst have a significant influence on the diastereoselectivity of this process9,16,71. 

The transformations in Table 2 illustrate that palladium(0)-catalyzed aminations proceed much faster for allyl chlorides than for allyl esters. The chloro acetates, readily available by diastereoselective palladium(II)-catalyzed 1,4-functionalization of 1,3-dienes27, thus give rise to the amino acetates in a highly chemo-, regio-, and diastereoselective fashion28-30. 

The reactions and product distributions thus far reported have been exclusively concerned with hexene. It was of interest to see whether the high specificity of positional substitution could be maintained with the other hexene isomers. By positional substitution specificity is meant ester attachment on ether of the carbons involved in the original carbon-carbon double bond. Table VII shows the results of these studies. The internal olefins reacted more slowly than the a-olefin, and with both palladium chloride-cupric chloride and 7r-hexenylpalladium chloride-cupric chloride systems high substitutional specificity (> 95% ) was also maintained with 2-hexene (Table VII). However, with 3-hexene the specificity is considerably lower (80%). Whether this is caused by 3-hexene isomerization prior to vinylation or by allylic ester isomerization is not known. A surprisingly high ratio of 2-substitution to 3-substitution is found ( 7 1) in the products from 2-hexene. An effect this large... 

Cobalt and Ni catalyze the carbonyiation of strained cyclic esters such as /3-propiolactone and butyrolactone . Palladium chloride carbonylates esters of allyl alcohol to 3-butenoic anhydrides at 100° and 9.6 MPa. ... 

A typical reaction involving nickel(O) treats an allylic halide such as 3-chloro-2-methyl-l-propene with Ni(CO)4 to form 439,288 a nickel dimer analogous to the palladium chloride dimer discussed in the previous section. This complex reacts with an alkene to form a new complex (440), and subsequent reaction with a variety of electrophilic reagents removes nickel. In this example, the chlorine was converted to an acetate ligand (in 441) and reacted with methanolic carbon monoxide to give the ester (442).288... 

Derivatives of carbohydrates that have been used to complex with rhodium catalysts to promote asymmetric hydrogenation include the phosphorus derivatives (6) and (7)/ and (8) (12) synthesized by esterification of the hydroxy-compounds with the appropriate phosphonyl chloride. Treatment of 7r-allyl-palladium chloride with the phosphite ester (13) gave a complex that was an enantioselective catalyst for hydrogenation of unsaturated acids and esters. ... 

Benzoic acid and substituted benzoic acids are readily thallated by thallium(III) trifluoroacetate. Subsequent reaction with palladium chloride and simple alkenes, allylic or vinyl halides, or vinyl esters result in the formation of isocoumarins eg ... 

Allyl chlorides and allyl esters react with TMSA in the presence of lithium perchlorate or a catal)dic amount of a palladium catalyst to give the corresponding allyl azides (eq 13). This transformation can also be used as a deprotection method for allyl esters. ... 

Cooper(I) carboxylates give esters with primary (including neopentyl without rearrangement), secondary, and tertiary alkyl, allylic, and vinylic halides. A simple Sn mechanism is obviously precluded in this case. Vinylic halides can be converted to vinylic acetates by treatment with sodium acetate if palladium(II) chloride is present. ... 

Allyl chlorides and bromides can be carbonylated to afford the respective unsaturated acids and esters with a variety of catalysts under relatively mild conditions such as 30-50 °C and 1 bar CO (Scheme 5.2). Most prominent are the palladium-containing catalysts and both [PdCl2(TPPMS)2] or [PdCl2(TPPTS)2] and [PdCl2(PPh3)2] were used, dissolved in the aqueous and in the organic phases, respectively [14-16]. 

To conclude, palladium on charcoal is only a precursor for soluble palladium species which are active in the carbonylation of allyl ethers. The formation of these species requires the presence of chloride and proceeds jointly with the generation of dimethyl carbonate. This catalyst could be reused but we have been unable so far to recover the ester selectivities achieved with fresh catalysts. The observation of a higher content of oligomeric materials in the reaction mixture resulting from the use of the recovered catalyst led us to suggest that an increase of the surface acidity of the carrier is presumably responsible for this increase in the oligomer content. 

Abnormal olefin arylation reactions which are of interest mechanistically and preparatively occur with some allylically substituted compounds. The ailylic esters and ethers appear normal and produce cinnamyl derivatives exclusively while ailylic alcohols and chlorides are abnormal. Ailylic alcohols and "arylpalladium acetates form 3-arylaldehydes from primary ailylic alcohols and 3-arylketones from secondary alcohols 3°). The mechanism of reaction apparently involves anti-Markovnikov addition of the palladium compound to the double bond followed by elimination of the hydrogen atom on the hydroxyl-bearing carbon rather than the benzylic hydrogen. This again would be elimination of the more electronegative hydrogen atom. 

A related one-pot three component coupling reaction leading to allyli-dene tetrahydrofuran derivatives 80 and which combines a conjugate addition of a propargyl alcohol with an activated olefin and an in situ palladium-catalyzed carbopalladation-cyclization in the presence of a large excess of allyl chloride has been recently developed by Lu and Iiu (Scheme 31) [77]. The cyclization process is here initiated by addition of a catalytic amount of Pd(OAc)2 and in marked contrast with the above-discussed reactions, a catalytic cycle involving divalent palladium proceeds in the reaction. In this process, the ester enolate formed in the Michael addition undergoes... 

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