Esters allylic alcohol

DKR requires two catalysts one for resolution and one for racemization. We and others have developed a novel strategy using enzyme as the resolution catalyst and metal as the racemization catalyst as shown in Scheme 1. The R-selecfive DKR can be achieved by combining a R-selective enzyme with a proper metal catalyst and its counterpart by the combination of the metal catalyst with a -selective enzyme. This strategy has been demonstrated to be applicable to the DKR of secondary alcohols, allylic esters, and primary amines. Among them, the DKR of secondary alcohols has been the most successful. 

Kaye CM. 1973. Biosynthesis of mercapturic acids from allyl alcohol, allyl esters, and acrolein. Biochem J 134 1093-1101. 

For example, allylic alcohols, allylic esters, allylic halides, and allylic tosylates. 

Complete chirality transfer has been observed in the intramolecular allyla-tion of an alcohol with the activated allylic ester of 2,6-dichlorobenzoic acid 338 to give the 2-substituted tetrahydrofuran 339[208]. 

It is possible to treat ketones with allyl alcohol and an acid catalyst to give y,5-unsaturated ketones directly, presumably by initial formation of the vinylic ethers, and then Claisen rearrangement.In an analogous procedure, the enolates (126) of allylic esters [formed by treatment of the esters with lithium isopropylcyclohex-... 

Selenium dioxide is a useful reagent for allylic oxidation of alkenes. The products can include enones, allylic alcohols, or allylic esters, depending on the reaction conditions. The mechanism consists of three essential steps (a) an electrophilic ene reaction with Se02, (b) a [2,3]-sigmatropic rearrangement that restores the original location of the double bond, and (c) solvolysis of the resulting selenium ester.183... 

In an analogous fashion to the reductive deprotection of allyl alcohols and allyl esters, the deallylation of allylamines is also possible (Eq. 337).270... 

Tricarbonyl( 1 -ewrfo-allyltetralin)chromium, stereoselective alcohol to hydrocarbon reduction, 132 1,2,3-Trideoxy-D-r/fco-hex-1 -enopyranose diacetate, allyl ester reduction,... 

The specificity of pectinesterase is not so marked with respect to the alcohol moiety of the ester, as it hydrolyzes ethyl esters of D-galacturonans at a rate 6-16% that of de-esterification of the methyl esters.36 Citrus natsudaidai pectinesterase de-esterifies the ethyl esters of pectic acid at a rate l/5th to l/7th of that for the methyl esters the propyl and allyl esters are attacked at l/20th to l/80th of the rate.38 The tomato, citrus, alfalfa, and papaya pectinesterases do not hydrolyze the glycol and glycerol esters of pectin.39... 

Related catalytic enantioselective processes It is worthy of note that the powerful Ti-catalyzed asymmetric epoxidation procedure of Sharpless [27] is often used in the preparation of optically pure acyclic allylic alcohols through the catalytic kinetic resolution of easily accessible racemic mixtures [28]. When the catalytic epoxidation is applied to cyclic allylic substrates, reaction rates are retarded and lower levels of enantioselectivity are observed. Ru-catalyzed asymmetric hydrogenation has been employed by Noyori to effect the resolution of five- and six-membered allylic carbinols [29] in this instance, as with the Ti-catalyzed procedure, the presence of an unprotected hydroxyl function is required. Perhaps the most efficient general procedure for the enantioselective synthesis of this class of cyclic allylic ethers is that recently developed by Trost and co-workers, involving Pd-catalyzed asymmetric additions of alkoxides to allylic esters [30]. 

The scope of reactions catalyzed by metalacychc iridium-phosphoramidite complexes is remarkably broad, but reactions with some substrates, such as allylic alcohols, prochiral nucleophiles, branched allylic esters, and highly substituted allylic esters, that would form synthetically valuable products or would lead to simpler symthesis of reactants occur with low yields and selectivities. In addition, iridium-catalyzed allylic substitution reactions are sensitive to air and water and must be conducted with dry solvents under an inert atmosphere. Several advances have helped to overcome some, but not aU of these challenges. 

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... 

Scheldt and co-workers have also illustrated the oxidation of activated alcohols to esters [132], Oxidations of alcohols such as 260 provide the electrophile (acyl donor) for a nucleophilic alcohol 261. Esters 262 are derived from propargylic, allylic, aromatic, and hetero-aromatic substrates (Table 20). The nucleophilic alcohol scope includes MeOH, n-BuOH, f-BuOH, 2,2,2-trichloroethanol, 2-methoxyethanol, and 2-(trimethylsilyl) ethanol. 

The Pd-catalyzed allylic alkylation of sulfinate ions, thiols, and thiocarboxylate ions with racemic cyclic and acyclic allylic esters in the presence of bisphosphane BPA generally provides for an efficient asymmetric synthesis of allylic sulfones, sulfides, and thioesters. The Pd-catalyzed rearrangements of allylic sulfinates and allylic O-thiocarbamates, both of which proceed very efficiently in the presence of BPA, are attractive alternative ways to the asymmetric synthesis of allylic sulfones and allyUc thioesters also starting from the corresponding racemic alcohols. 

Allyl esters, carbonates, and carbamates readily undergo C-O bond cleavage upon reaction with palladium(O) to yield allyl palladium(II) complexes. These complexes are electrophilic and can react with nucleophiles to form products of allylic nucleophilic substitution. Linkers based on this reaction have been designed, which are cleavable by treatment with catalytic amounts of palladium complexes [165,166], For the immobilization of carboxylic acids, support-bound allyl alcohols have proven suitable (Figure 3.12, Table 3.7). 

Hydroformylation - [CARBON MONOXIDE] (Vol 5) - [OXO PROCESS] (Vol 17) -of allyl alcohol [ALLYL ALCOHOL AND MONOALLYL DERIVATIVES] (Vol 2) -catalysts for [CATALYSIS] (Vol 5) -C-19 dicarboxylic acids from [DICARBOXYLIC ACIDS] (Vol 8) -of ethylene [ETHYLENE] (Vol 9) -of ethylene [PROPYL ALCOHOLS - N-PROPYLALCOLHOL] (Vol 20) -of maleate and fumarate esters [MALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) -phosphine catalyst [PHOSPHORUS COMPOUNDS] (Vol 18) -platinum-group metal catalysts for [PLATINUM-GROUP METALS] (Vol 19) -rhodium catalysis [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19) -ruthenium cmpds or catalyst [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19) -use of coordination compounds [COORDINATION COMPOUNDS] (Vol 7)... 

Reduction of halides.1 The reagent prepared from NaBH3CN and SnCl2 in a 2 1 ratio does not reduce primary or secondary alkyl halides or aryl halides in ether at 25°, but does reduce tertiary, allyl, and benzyl halides. It is thus comparable to NaBH3CN-ZnCl2 (12, 446). Aldehydes, ketones, and acid chlorides are reduced to alcohols, but esters and amides are inert. 

Copper(I) sulfate generated from the reduction of aqueous copper(II) sulfate with metallic copper promotes the epoxidation of alkenes such as allyl alcohol or propene in low yields.585 The reaction of /-butyl hydroperoxide or /-butyl peracetate with alkenes in the presence of copper(I) chloride results in the homolytic formation of allylic /-butyl peroxides or allylic esters (equations 258-260). 

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