Allylic reactions Tetrakis palladium

Dialkylindolines and 1,3-dialkylindoles are formed in poor yield (<10%) from the reaction of ethyl- or phenymagnesium bromide with 2-chloro-N-methyl-N-allylaniline in the presence of catalytic quantities of (bistriphenylphosphine)nickel dichloride.72 In a modification of this procedure, the allyl derivatives can be converted by stoichiometric amounts of tetrakis(triphenylphosphine)nickel into 1,3-dialkylindoles in moderate yield72 (Scheme 43) an initial process of oxidative addition and ensuing cyclization of arylnickel intermediates is thought to occur. In contrast to the nickel system,72 it has proved possible to achieve the indole synthesis by means of catalytic quantities of palladium acetate.73 It is preferable to use... 

Substitution reactions of allylic nitro compounds often lead to rearranged products, as in palladium(0)-catalysed aminations and alkylations. Thus treatment of the nitro ester 419 with piperidine in the presence of tetrakis(triphenylphosphine)palladium yields a mixture of the unrearranged and rearranged amines 420 (R = piperidin-l-yl) and 421... 

The oxidative addition is quite general with alkyl, allyl, benzyl, vinyl, and aryl halides as well as with acyl halides to afford the palladium (II) complex VII. The frans-bis( triphenylphosphine )alkylpalladium halides can also be carbonylated in an insertion reaction to give the corresponding acyl complexes, the stereochemistry of which (17, 18) proceeds with retention of configuration at the carbon bonded to palladium. The acyl complex also can be formed from the addition of the corresponding acid halide to tetrakis (triphenylphosphine) palladium (0). 

Tetrakis(triphenylphosphine)-palladium(O), 289 Tin(IV) chloride, 300 Trimethylamine N-oxide, 325 Zinc amalgam, 347 Homoallylic alcohols By addition reactions of allyl to carbonyl groups... 

Stereoselective allylic alkylations have been carried out with the aid of palladium catalysts. The 17-(Z)-ethylidene groups of steroids (obtained from the ketones by Wittig olefination) form n-allyl palladium complexes in the presence of copper(n) salts (B.M. Trost, 1974, 1976). Their alkylation with dimethyl malonate anions in the presence of 1,2-ethane-diylbis[diphenylphosphine] (— diphos) gives a reaction exclusively at the side chain and only the (20S) products. If one starts with the endocyclic 16,17 double bond and replaces an (S)-20-acetoxy group by using tetrakis(triphenylphospbine)palladium,the substitution occurs with complete retention of configuration, resulting from two complete inversions (B.M. Trost, 1976). 

In 1995 Pyne and Dong95 found that the ally lie sulfoximine 165 underwent a facile and completely regioselective and efficient rearrangement to the allylic sulfinamide 166 in the presence of tetrakis(triphenylphosphine)palladium(0) ((PPh3)4Pd) catalyst (5 mol%) at room temperature. Mild base hydrolysis of the reaction mixture (10% aqueous sodium hydroxide/methanol, 1 10, room temperature, 2 h) gave pure sulfonamide 167 after purification by column chromatography (silica gel) in 90% overall yield. 

Enantioselective Allylic Alkylation. Reaction of l-(a-acet-oxyethyl)cyclopentene with the sodium salt of dimethyl mal-onate in refluxing 1,2-dimethoxyethane, when performed in the presence of tetrakis(triphenylphosphine)palladium and (R,S)-CAMPHOS catalyst, afforded the corresponding ct-alkylated malonic ester in 99% chemical yield (37% ee)(eq 3). Comparable results were obtained when this reaction was performed in THF solution by using Pd(PPh3)4-(S,S)-(+)-DIOP as catalyst. ... 

The stereoselective allylation of aldehydes was reported to proceed with allyltrifluorosilanes in the presence of (S)-proline. The reaction involves pentacoordinate silicate intermediates. Optical yields up to 30% are achieved in the copper-catalyzed ally lie ace-toxylation of cyclohexene with (S)-proline as a chiral ligand. The intramolecular asymmetric palladium-catalyzed allylation of aldehydes, including allylating functionality in the molecules, via chiral enamines prepared from (5)-proline esters has been reported (eq 15). The most promising result was reached with the (S)-proline allyl ester derivative (36). Upon treatment with Tetrakis(triphenylphosphine)palladium(0) and PPh3 in THF, the chiral enamine (36) undergoes an intramolecular allylation to afford an a-allyl hemiacetal (37). After an oxidation step the optically active lactones (38) with up to 84% ee were isolated in high chemical yields. The same authors have also reported sucessful palladium-catalyzed asymmetric allylations of chiral allylic (S)-proline ester enamines" and amides with enantiomeric excesses up to 100%. 

Kosugi, M., Sasazawa, K., Shimizu, Y., Migita, T. Reactions of allyltin compounds. III. Allylation of aromatic halides with allyltributyltin in the presence of tetrakis(triphenylphosphine)palladium ° . Chem. Lett. 1977, 301-302. 

Coupling of allyl bromides and aUylstannanes. This reaction is possible by catalysis with benzylchlorobis(triphenylphosphine)palladium, which is probably converted into bis(triphenylphosphine)palladium(0), the actual catalyst. This Pd(0) complex is more effective than tetrakis(triphenylphosphine)palladium(0). Zinc chloride in certain cases can function as a catalyst alone or in combination with the Pd(II) catalyst.1... 

Coupling of allylstannanes and allyl acetates.5 This reaction is also catalyzed by tetrakis(triphenylphosphine)palladium. 

The palladium-catalyzed system can be extended to the acylation of siloxycyclopropanes with aroyl chloride/carbon monoxide or aryl triflate/carbon monoxide, which gives 1,4-diketones. Contrary to the case of doubly oxygen-substituted cyclopropanes vide infra), the acylation of 1-siloxycyclopropanes is restricted to aroyl chlorides and is not applicable to aliphatic or a, -unsaturated acyl chlorides. For the reactions with aryl triflates, tetrakis(triphenylphos-phane)palladium(O) is used as catalyst, while the reactions with aroyl chlorides employ bis(triphenylphosphane)palladium(II) chloride and ( / -allyl)chloropalladium dimer/triphenyl phosphite as catalysts. In these reactions, aroylpalladium(II) species may undergo ring opening of the siloxycyclopropanes. 

Joint catalysis by tin(IV) chloride and zinc chloride induces coupling of the acetal 114 with the alkyne 115 to give the propargyl ether 116. Allyl halides condense with terminal alkynes in DMF in the presence of copper(I) iodide, potassium carbonate and tetrabutylammonium chloride under phase-transfer conditions to afford eneynes, e.g. equation 19. Palladium-catalysed coupling reactions of 1-bromoallenes with terminal acetylenes have been reported for the first time thus acetylene and the allenes 117 (R R = Me or Et) in triethylamine in the presence of tetrakis(triphenylphosphine)palladium and... 

Chiral allylic cyclic carbonates such as 551 or 552 undergo excellent regioselective alkylation reactions with soft nucleophiles in the presence of palladium(O) in refluxing THF to provide ( )-allylic alcohols. The reaction of 4-0-benzyl-2,3-isopropylidene-L-threose (167) with the appropriate ylid, followed by deprotection of the isopropylidene ring with acidic resin and cyclic carbonate formation, provides a good overall yield of either 551 or 552. Ring opening with diethyl malonate in the presence of tetrakis(triphenylphosphine)palladium(0) provides in excellent yield the allylic alcohols 553 or 554, where the diastereoselectivity exceeds 99%. This reaction represents an efficient method of 1,3-chirality transfer [180] (Scheme 122). 

Palladium-Catalyzed Coupling Reaction with Organo-halides. In the presence of tetrakis(triphenylphosphine)-palladium(O), vinyl halides (12) are converted to the corresponding vinylsilanes (13) with the aid of MegSi2 and tris-(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) in 53-92% yields with high chemoselectivity and stereospecificity (eq 6). Similarly, aryl-, benzyl-, and allylsilanes are obtained from the corresponding halides in 57-100, 8 8, and 52-93% yield, respectively. Allyl esters also are transformed by Pd-catalyzed reaction of Me6Si2 into allylsilanes. ... 

TMS-alkynes are oxidized at the terminal carbon to carboxylic acids by hydroboration/oxidation (dicyclohexylborane/NaOH, H2O2). This does not work with TIPS-alkynes. Instead, TIPS-alkynes are cleanly monohydroborated at the internal carbon by 9-borabicyclo[3.3.1]nonane dimer to give (Z)- -borylvinyl-silanes. These can be oxidized in high yields to a-silyl ketones, or cross coupled with a bromide R Br (R = aryl, benzyl, dimethyl-vinyl) in the presence of NaOH and tetrakis(triphenylphos-phine)palladium(0) to give /3,/3-disubstituted vinylsilanes (Suzuki reaction eq 14). The same nucleophilic substituted vinylsilane can be added to an aromatic aldehyde to provide access to ( )-3-silyl allyl alcohols. ... 

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