Esters, allylic, reaction with

Mowery and DeShong used the commercially available hypervalent silicate complex TBAT as a phenylating agent for the cross-coupling reaction with allylic esters. They later reported on the use of the same organosilane for the coupling with aryl iodides and triflates and electron-deficient aryl bromides. The reactions were catalyzed by either Pd(dba)2 or [Pd(allyl)Cl]2 without the need of added phosphine ligands. 

Addition to double bonds. Alkenes react with TeCl to give mainly products of svn-addition of Cl and TeCl,. Only Markownikoff addition occurs with terminal alkenes. The reaction with allylic esters is unusual it involves. svn-1.3-addition with a 1,2-rear-... 

The possible use of organocuprate reactions with allylic esters as a way to create carbon-carbon bonds at C6 positions of pyranoses has already been mentioned [55]. This has been applied... 

In connection with the finding that a combination of a Pd catalyst and ammonium formates is effective for hydrogenolysis of allyl esters to olefins, and of propargyl carbonates to allenes, the reactions with allyl ester of alkynyl acid and propargyl acetate under the reaction conditions shown in Scheme 4 were investigated. The results indicate that in both cases reduction of the triple bond takes preference over hydrogenolysis as sununa-rized in Scheme 5. 

Carbohydrate lactones have been used as the carbonyl reagent in the Reformatsky reaction. Thus, 2,3 5,6-di-O-cyclohexylidene-D-mannono-1,4-lactone [44, obtained by oxidation of the mannofuranose derivative (49)] reacted with ethyl bromoacetate and zinc to give the protected 2-deoxy-3-octulosonic acid ethyl ester (45a) in 69% yield (50). Ketonic hydrolysis with potassium hydroxide in aqueous methanol, followed by acidification and heating, afforded the 1-deoxyheptulose derivative 45b. Similarly, starting from compound 44, the 1-C-substituted allyl and propar-gyl lactols were prepared on reaction with allyl or propaigyl bromides in the presence of zinc (51). 

Most iridium-catalyzed allylic substitutions have been performed with allylic esters, which are typically synthesized from allylic alcohols. Reactions of allylic alcohols as electrophiles would alleviate the need to prepare the esters from the alcohol. In a few cases, however, iridium catalyzed allylic substitutions have been conducted with allylic alcohols as the electrophile. As discussed earlier in this... 

Rearrangement of allyl trimethylsilyl ketene acetal, prepared by reaction of allylic ester enolates with trimethylsilyl chloride, to yield Y,5-unsaturated carboxylic a-cids. The Ireland-Claisen rearrangement seems to be advantageous to the other variants of the Claisen rearrangement in terms of E/Z geometry control and mild conditions. 

The first formed enolate products from hydrodimerization of esters are trapped by reaction with added chlorotrimethylsilane. By starting with allyl esters, this hy-... 

A reaction which is related to the ortho ester Claisen rearrangement utilizes an amide acetal, such as dimethylacetamide dimethyl acetal, rather than an ortho ester in the exchange reaction with allylic alcohols.174 The stereochemistry of the reaction is analogous to that of the other variants of the Claisen rearrangement.175... 

Reactions of Grignard Reagents with Allylic Esters and Ethers... 

A prototypical study for this section has been obtained as early as in 1983 for carbonylative cross-coupling of the mixture of aryl iodide and alkyl iodide in the presence of Zn metal and palladium catalyst. This system apparently works due to differences of reactivity of aryl versus alkyl iodide toward metallation by Zn. Further studies were rather scarce to involve only preformed functionalized alkylzincs. Carbonylative cross-coupling of functionalized organozinc reagents with allylic esters and GO (1 atm) can be carried out in THF in the presence of HMPA, which suppresses side-reactions (Scheme 4). ... 

Michael addition reactions, 4, 302 reactions with allyl halides, 4, 301 Pyrrole-2-carboxylic acid, 1-methyl-conformation, 4, 194 esters... 

Hydroxysulphenylation. The reaction of these two reagents in CH2Cl2/tri-fluoroacetic acid with allylic esters gives vic-trifluoroacetoxy sulfides, which are hydrolyzed to vic-hydroxy sulfides. The reaction with allyl acetate (equation I)... 

Micalizio and Schreiber [47] developed a key reaction, the transesterification of unsaturated boronic esters with allylic esters or propargylic alcohols. This reaction transiently provided mixed organoboronic esters that could be trapped by using... 

The Kharasch-Sosnovsky reaction may be carried out in the presence of carboxylic acids to introduce the acyloxy moiety of the acid used, and may also be conducted photochemically at room temperature using UV irradiation. Peioxy acids,diacyl peroxides, and peroxyphosphates and peroxyphospho-nates are alternative oxidants. /-Butyl hydroperoxide may also be used in place of peroxy esters with broadly similar results, although formations of mixed peroxides and /-butyl ethers can then compete with allyl ester production. 

Selenium and tellurium reagents have been used for stereoselective halogenations of alkenes. For example, trans addition of benzeneselenenyl chloride to alkenes followed by the displacement of the seleno moie with chloride can lead to dr-1,2-dichlorides (equation 25). The addition of 2-naph-thyltellurium trichloride proceeds in an anti stereospecific manner (equation 26), whereas tellurium tetra-diloride gives a mixture of syn and anti adducts. The reaction of allyl esters with tellurium tetrachloride accompanies acyl migration to give the l-(trichloiottlluro)-3-chk>io adduct (54 equation 27). ... 

The reactions of this section use stabilized carbanions formed from C—H-addic compounds by deprotonation. As phosphines are the only successful ligands known up to now, these reactions have been discussed in detail in Chapter 2, and we will again restrict this section to a few highlights. Carbanions derived from 1,3-diketones react with allylic esters enantioselectively under palladium catalysis with more than 80% ee [175]. Benzylamine is allylated by the same catalytic system, leading to substituted allyl-benzylamines with up to 97% ee (Fig. 4-32c) [176]. 

Type III reaction proceeds by an attack of a nucleophile at the central sp carbon of the allenylpalladium. In contrast to facile Pd(0)-catalyzed reactions of allylic esters with soft carbon nucleophiles via TT-allylpalladium intermediates, propargylic esters are less reactive towards soft carbon nucleophiles. No reaction of soft carbon nucleophiles occurs with propargylic acetates. However, soft carbon nucleophiles such as -keto esters and malonates react with propargylic carbonates under neutral conditions using dppe as a ligand [43]. 

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