Allylic Alcohol Isomerization

Allyl alcohol isomerization is typically conducted as a single-phase reaction, needing efforts for separation of the catalyst [110, 113], One driver was to exploit a catalyzed liquid/liquid route with aqueous (catalytic) and organic phases as commonly employed in the chemical industry. 

Figure 4.65 Parity plot comparing the conversion of a batch and laminar flow model for five different substrates made by allyl alcohol isomerization. For calculation, the same rate law was used for all substrates. The increase in conversion is due to increased substrate solubility [112].

Figure 7.11 presents the mechanism of propylene oxide synthesis by allyl alcohol isomerization. This assumption correlates well with experimental data the kinetic curve shape... 

Heterogeneous copper catalysts prepared with the chemisorption-hydrolysis technique are effective systems for hydrogen transfer reactions, namely carbonyl reduction, alcohol dehydrogenation and racemization, and allylic alcohol isomerization. Practical concerns argue for the use of these catalysts for synthetic purposes because of their remarkable performance in terms of selectivity and productivity, which are basic features for the application of heterogeneous catalysts to fine chemicals synthesis. Moreover, in all these reactions the use of these materials allows a simple, safe, and clean protocol. 

The intra/intermolecularity of the allylic alcohol isomerization has been investigated through a crossover labeling study employing allyl-3- C alcohol 8,... 

This catalytic system is also applicable to isomerization of allylic alcohols. Under reaction conditions which are the same as, or milder than, those for the rearrangement of homoallylic alcohols, the allylic alcohols isomerized rapidly [12bj. 

The observed ees are in the range 64-86%. Z-allylic alcohols isomerize with higher ees than the E-allylic counterparts. This process has been applied to the synthesis of two naturally-occurring sesquiterpenes. It is interesting to note here that the highest ee previously reported for such an isomerization (53%) employed an Rh+/BINAP catalyst where a modest yield (47%) was also observed [76]. 

An allylic alcohol isomerized during an enzymatic esterification (10.25).47... 

The most thoroughly investigated group of oxotropic isomerizations are those of allylic alcohols. Braude, who conducted extensive studies of allylic alcohol isomerizations. reviewed them in 1950. 

Observed Arrhenius activation parameters for allylic alcohol isomerizations are also consistent with a unimolecular rate-limiting step. In aqueous ethanol and aqueous dioxane, differences in reactivity due to structural changes in the allylic system are reflected primarily in the energy of activation. Values of entropy of activation are generally near Harris... 

Kinetic studies of racemization of optically active allylic alcohols, of isotope exchange of 0-labeled allylic alcohols, and of cis-trans isomerization of suitably substitued allylic alcohols have contributed to knowledge of the detailed mechanism and stereochemistry of allylic alcohol isomerization. 

Leung DH, Bergman RG, Raymond KN. Highly selective supramolecular catalyzed allylic alcohol isomerization. J Am Chem Soc 2007 129 2746-7. 

Related to the alkene-to-allylic alcohol conversion is the oxiran to allylic alcohol isomerization. Two recent reports describe the use of trimethylsilyl iodide, either ready-made or prepared in situ from hexamethyldisilane and iodine, with DBU (Scheme 12) the initially formed 2-iodo-alkoxysilane (31) eliminates HI to give an allylic silyl ether that is cleaved during hydrolytic work-up. An alternative procedure (also Scheme 12) employs t-butyldimethyl-silyl iodide, generated in situ according to equation (14), and DBN. In this... 

Allylic Alcohol Isomerization. Nitric acid has been shown to be effective for the isomerization of allylic alcohols (eq 29). It is necessary to use short reaction times in order to avoid the competing dehydration reaction. Unfortunately, mixtures of E-and Z-double bonds are obtained. 

The caged organorhodium cation 421, generated in situ by Scheme 5.17, has been used [17] for catalyzing allylic alcohol isomerization of... 

The caged (CH3)3PAu cation also catalyzes with high turnovers of the allyl alcohol isomerization in aqueous solutions by Scheme 5.26, performing more than 1000 catalytic cycles [24]. 

The dendrimer-supported catalysts described in Sect. 7.5 were also tested in allylic alcohol isomerization. Isomerization of l-octen-3-ol into octan-3-one was... 

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