AUyl alcohols addition reactions

In addition to the catalysts listed in Table 2, several rhodium(I) complexes of the various diphosphines prepared by acylation of bis(2-diphenylphosphinoethyl)amine were used for the hydrogenation of unsaturated acids as well as for that of pyruvic acid, aUyl alcohol and flavin mononucleotide [59,60]. Reactions were mn in 0.1 M phosphate buffer (pH = 7.0) at 25 °C under 2.5 bar H2 pressure. Initial rates were in the range of 1.6-200 mol H2/molRh.h. 

Maruoka has found that simple alcohols can also be used in the oxy-Michael reaction [107], Using the axially chiral biaryl catalyst 67 (1 mol%) the conjugate addition of methanol, ethanol and aUyl alcohol to a, 3-unsaturated aldehydes was examined (Scheme 29). Despite moderate yields (55-83%) and enantioselectivities (16-53% ee), the high activity of this catalyst suggests that further optimisation... 

Allyl alcohol undergoes reactions typical of saturated, aliphatic alcohols. Allyl compounds derived from allyl alcohol and used industrially, are widely manufactured by these reactions. For example, reactions of aUji alcohol with acid anhydrides, esters, and acid chlorides yield aUyl esters, such as diaUji phthalates and allyl methacrylate reaction with chloroformate yields carbonates, such as diethylene glycol bis(allyl carbonate) addition of allyl alcohol to epoxy groups yields products used to produce allyl glycidyl ether (33,34). 

The process involving ahyl alcohol has not been industrially adopted because of the high production cost of this alcohol. However, if the aUyl alcohol production cost can be markedly reduced, and also if the evaluated cost of hydrogen chloride, which is obtained as a by-product from the substitutive chlorination reaction, is cheap, then this process would have commercial potential. The high temperature propylene—chlorination process was started by Shell Chemical Corporation in 1945 as an industrial process (1). The reaction conditions are a temperature of 500°C, residence timp 2—3 s, pressure 1.5 MPa (218 psi), and an excess of propylene to chlorine. The yield of allyl chloride is 75—80% and the main by-product is dichloropropane, which is obtained as a result of addition of chlorine. Other by-products include monochloropropenes, dichloropropenes, 1,5-hexadiene. At low temperatures, the amount of... 

The Mukaiyama aldol reaction involves the addition reaction of a TMS-enol ether to an aldehyde. Loh et al. have investigated the reaction of l-methoxy-2-methyl-l-trimethylsiloxypropene with aliphatic and aromatic aldehydes in chloride, [BF4] and [PFg] ionic liquids. The yields varied considerably and it was found that the chloride ionic liquids gave the best yields (50-74%) [230]. Ruthenium complexes have been used in the addition of aUyl alcohols to aldehydes and imines in [BMIM][Pp6] [231] (and later in a very similar paper [232]). The addition of a cootalyst such as indium(iii) acetate was found to dramatically improve the yields in some cases and it was foimd that the ionic Uquid/catalyst combination could be recycled. Examples of these reactions are shown in Scheme 5.2-100. 

The process from the FMC company involves as the pivotal step an intramolecular stereoselective [2 + 1 [-cycloaddition. In a Prins reaction [94] of chloral and isobutene, followed by an isomerisation, a racemic, trichloromethyl-substituted aUyl alcohol is obtained. Reaction with the isocyanate from (R)-naphthylethyl-amine enables separation ofthe diastereomers by crystallisation. The carbamate is cleaved by trichlorosilane/triethylamine, thus permitting the recycling of the chiral auxiliary. The optically pure (R)-aUyl alcohol is reacted with diketene, to produce the / -keto-ester. After diazo transfer and basic cleavage, the diazoacetate is obtained catalysed by a copper salt, this is converted in a [2 + 1 ]-cyclo-addition into a bicyclic lactone. The Boord reaction (discovered by Cecil E. Boord in 1930) [95] finally gives (IR)-cis-permethric acid. [96]... 

Enantiosdective allyic substitution processes have been developed over the course of 30 years. Initial observations of the reactions of nucleophiles with paUadium-allyl complexes led to the observation of catalytic substitutions of aUylic ethers and esters, and then catalytic enantioselective aUylic substitutions. The use of catalysts based on ottier metals has led to reactions that occur with complementary regiochemistry. Moreover, flie scope of the reactions has expanded to include heteroatom and unstabilized carbon nucleophiles. Suitable electrophiles for these reactions indude allyhc esters of various types, allyhc ethers, aUylic alcohols, and aUylic halides. Enantioselective reactions can be conducted with monoesters or by selection for deavage of one of two equivalent esters. The mechanism of these reactions occurs by initial oxidative addition to form a metal-aUyl complex. The second step involves nudeophilic attadc on ttie aUyl ligand for reaction of "soft" nudeophiles or inner-sphere reductive eUmination for reactions of "hard" nudeophiles. The external nudeophilic attack typicaUy occurs by reaction of the nudeophile with a cationic aUyl complex at the face opposite to that to which Uie metal is bound. Exceptions indude reactions of certain molybdenum-aUyl complexes. Dissociation of product then regenerates the starting catalyst. Because of the diversity of the classes of these reactions, aUylic substitution—in particular asymmetric aUylic substitution—has been used to prepare a wide variety of natural products. 

The impact of silver(l) and thaUium(I) salts [221] on Pd-catalyzed reactions extends beyond just increasing regioselectivities and enhancing reaction rates [202]. Without these additives, the arylation of aUyl alcohols 27 afforded aldehydes and ketones 30, rather than the fS-arylaUyl alcohols 33 (Scheme 8.7). Apparently, the P-hydride ehmination in the intermediate 28 is faster in the direction leading to enol 31. Alternatively, p-hydride ehmination to give the allyl alcohol 33 followed by readdition of the hydridopalladium species to the double bond and subsequent P-hydride ehmination to give the more stable enol 31 would explain the facts. This... 

The first direct addition of a nucleophihc allylpalladium complex to aldehydes was published in 1996 by Yamamoto et al. [139]. Later on, Wallner and Szabo [7c, 140] have reexamined the regio- and stereoselectivities of the reaction employing density functional theory (DFT) computations. The intermediate it-allylpalladium complex 122 is generated by the reaction of an aUyl acetate (or chloride) 121 with hexamethylditin in the presence of allylpalladium chloride dimer (Scheme 12.58). The bis-aUylic system thus generated can then transfer a nucleophilic allyl fragment to the aldehyde 123. The reaction of bis-allylpalladium reagents generally yields branched homoallyUc alcohols 124 with prevalent anti diastereoselectivity. 

The aUyl moiety of allylic acetate undergoes nucleophilic addition to aldehydes and provides homoallyl alcohols in good to moderate yield in the presence of 2 mol % of PdCl2(PhCN)2 and 3 equiv of tin(ll) dichloride in DM1 (l,3-dimethyl-2-imidazolidinone) at 25-60 °C (Scheme The reaction displays high chemoselectivity and the aldehyde moiety of 10-oxoundecanal is selectively aUylated under the conditions shown in Scheme 5. 

Nucleophilic Displacement. PhTMS-BF3 0Et2 system has been shown to be useful in the transformation of allylic alcohols to allylic sulfides (eq IS). Preparation of unsymmetrical diaryl sulfides can be achieved by reaction of arenediazonium tetraflu-oroborates with PhSTMS (eq 19). In some cases, addition of cupric sulfide increases the yield of the diaryl sulfides. The use of (phenylthio)trimethylsilane as a coupling partner in palladium catalyzed reactions with aUyl carbonates (eq 20) and aryl iodide (eq 21) has been explored. ... 

Addition to Ketones and Aldehydes. o -(Trimethylsilyl)-vinyUithium 1 adds to ketones and aldehydes. The adducts do not undergo the expected Peterson elimination reaction when treated with sodium hydride or potassium hydride, but the corresponding aUene can stiU he obtained if the alcohol is converted to the chloride followed by fluoride-catalyzed -elimination (eq 1). Other uses have also been made of the aUyl chlorides made in this manner they react with cuprates, or they can be oxidized to the epoxides to serve as precursors to aUene oxides. ... 

Gabriele et al. reported a sequential homobimetallic palladium-catalyzed cascade reaction for the synthesis of benzofuran derivatives 207 [80] (Scheme 6.57). Sequential homobimetallic catalysis is different in catalytic cycles promoted by the same metal but in different oxidation states. After oxidative addition and oxopalladation, 5-exo-dig cyclization occurs, followed by carbonylation, affording the intermediate 206. The allylic alcohol is reduced by H—Pd—I through formation of a ji-aUyl complex and the elimination of water. Finally, the product observed is afforded... 

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