Carbonylation of allyl alcohol

Carbonylation of allylic alcohols requires severe conditions[248]. The carbonylation of allylic alcohols proceeds smoothly in the presence of LiCl and Ti(IV) isopropoxide[249j. The allylic methyl ether 394 can be carbonylated with the use of PdCl2[250] or 7r-allylpalladium coordinated by BF4, PF, and... 

Less reactive allylic alcohols are carbonylated under harsh conditions. However, carbonylation of allylic alcohols proceeds smoothly in the presence of phenol as a nucleophile. Phenyl 4-phenyl-3-butenoate (374) was obtained in 80 % yield from cinnamyl alcohol under 5 atm of CO at 100 °C. The carbonylation may proceed by the formation of allyl phenyl ether, which is a reactive compound [145]. Allyl alcohol was carbonylated under high pressure of CO2 (50 atm) and CO (50 atm) in dioxane to provide 2-butenoic acid as the main product and 3-butenoic acid as the minor product at 110°C. Presumably monoallyl carbonate 375 is generated from... 

Scheme 6.22 Ruthenium-catalyzed oxidative carbonylation of allylic alcohols...

Alper and Leonard reported carbonylations of allylic alcohols under oxidative conditions using PdCl2, HCl, O2, and CUCI2 in The reaction requires both oxygen and... 

The carbonylation of nitrobenzene to phenyl isocyanate is catalysed by [RhCl(CO)2]2 + L (L=MoCl6 or py.H+Cl- >), [RhH(CO)(PPh3)3], = and PdCl2-pyMe+ Carbonylation of allylic substrates has also been studied in detail rhodium phosphine complexes [e.g., RhCl(PPh3)s] are particularly useful for the synthesis of AT-alkyl-2-pyrrolidones [reactions (6)], whereas the carbonylations of allylic alcohols to vinylacetate esters [reaction (7)] are best carried out with [PdCl2(PAr3)a]10MCl2 (M=Sn or Ge). ... 

Another route to the diol monomer is provided by hydroformylation of allyl alcohol or allyl acetate. Allyl acetate can be produced easily by the palladium-catalyzed oxidation of propylene in the presence of acetic acid in a process similar to commercial vinyl acetate production. Both cobalt-and rhodium-catalyzed hydroformylations have received much attention in recent patent literature (83-86). Hydroformylation with cobalt carbonyl at 140°C and 180-200 atm H2/CO (83) gave a mixture of three aldehydes in 85-99% total yield. 

The isomerization of allylic alcohols provides an enol (or enolate) intermediate, which tautomerizes to afford the saturated carbonyl compound (Equation (8)). The isomerization of allylic alcohols to saturated carbonyl compounds is a useful synthetic process with high atom economy, which eliminates conventional two-step sequential oxidation and reduction.25,26 A catalytic one-step transformation, which is equivalent to an internal reduction/oxidation process, is a conceptually attractive strategy due to easy access to allylic alcohols.27-29 A variety of transition metal complexes have been employed for the isomerization of allylic alcohols, as shown below. 

Various ruthenium complexes catalyze the isomerization of allylic alcohols to saturated carbonyl compounds. Ru(acac)3 is an effective catalyst for the isomerization of a wide range of allylic alcohols (Scheme 12).35... 

The plausible mechanism of this ruthenium-catalyzed isomerization of allylic alcohols is shown in Scheme 15. This reaction proceeds via dehydrogenation of an allylic alcohol to the corresponding unsaturated carbonyl compound followed by re-addition of the metal hydride to the double bond. This mechanism involves dissociation of one phosphine ligand. Indeed, the replacement of two triphenylphosphines by various bidentate ligands led to a significant decrease in the reactivity.37... 

Run(H20)6(tos)2 is an efficient catalyst for the isomerization of allylic alcohols and allylic ethers under mild conditions in aqueous media to yield the corresponding carbonyl compounds.39... 

A very extensive and detailed study of the cationic rhodium(i)-catalyzed isomerization of allylic alcohols demonstrated that mono- and disubstituted allylic alcohols can be efficiently isomerized to the corresponding carbonyl compounds through the corresponding enol compounds (Scheme 20).45 The isomerization using cationic rhodium(l)... 

The mechanistic study revealed that the isomerization of allylic alcohols to the corresponding enols proceeds through a 7r-allyl intermediate (Scheme 21), and the isomerization of the enols to the corresponding carbonyl compounds proceeds through an oxy-7r-allyl intermediate (Scheme 22).45... 

Various nucleophiles other than methanol can be introduced onto the carbonyl carbon. Anodic oxidation of acylsilanes in the presence of allyl alcohol, 2-methyl-2-propanol, water, and methyl /V-methylcarbamate in dichlorometh-ane affords the corresponding esters, carboxylic acid, and amide derivatives (Scheme 24) [16]. Therefore, anodic oxidation provides a useful method for the synthesis of esters and amides under neutral conditions. 

Thermodynamic and kinetic data for Cope rearrangements leading to allenes have been measured [511]. For preparatively useful yields the equilibrium can be shifted to the allene, for example by the classical use of allylic alcohols leading to carbonyl compounds [512],... 

Furthermore, the reaction of allyl alcohols 67 and vinyl or isopropenyl acetates 68 was reported to afford y,5-unsaturated carbonyl compounds 70 (Equahon 10.13) [29]. 

Reactions where NLE have been discovered include Sharpless asymmetric epoxi-dation of allylic alcohols, enantioselective oxidation of sulfides to sulfoxides, Diels-Alder and hetero-Diels-Alder reactions, carbonyl-ene reactions, addition of MesSiCN or organometallics on aldehydes, conjugated additions of organometal-lics on enones, enantioselective hydrogenations, copolymerization, and the Henry reaction. Because of the diversity of the reactions, it is more convenient to classify the examples according to the types of catalyst involved. 

Allylic acetates are usually prepared by esterification from allylic alcohols. However, the corresponding alcohols are often only accessible by the fairly expensive hydride reduction of carbonyl compounds. Consequently, direct allylic functionalization of easily available olefins has been intensively investigated. Most of these reactions involve peroxides or a variety of metal salts.However, serious drawbacks of these reactions, (e.g. toxicity of some metals, stoichiometric reaction conditions, or nongenerality) may be responsible for their infrequent use for the construction of allylic alcohols or acetates. 

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