Payne rearrangement, of epoxy alcohol

The Payne rearrangement of epoxy-alcohols is a special case of an intramolecular nucleophilic opening of epoxides and is of particular synthetic utility when it is applied to epoxides from the Sharpless procedure. ... 

Although the Payne rearrangement usually produces mixtures of epoxy alcohols, because the rate of reaction of 2 with any given nucleophile is faster than that of i, the l,2-epoxy-3-alcohols generated in situ can be selectively and irreversibly captured by a nucleophile to afford 3. 

Cyclization of halohydrins 0-16 Cyclization of 1,2-diols 0-18 Payne rearrangement of 2,3-epoxy alcohols... 

Glycidol, like all 2,3-epoxy alcohols, is susceptible to the Payne rearrangement when exposed to base. Payne rearrangement of (/ )-or (S)-glycidol is degenerate consequently racemization does not occur. 

In the following case, there was no indication of any Payne rearrangement of the epoxy alcohol. ... 

Scheme 10.1 Payne rearrangement of simple 2.3-epoxy alcohols.

Scheme 10.21 Payne rearrangement of stereoisomeric 2.. -epoxy alcohols with a CFo group.

Table 10.2 Stereodivergent Synthesis of Epoxy Alcohols (E)-92 and Their Payne Rearrangement Tsee Scheme 10.211...

The Payne rearrangement of the respective epoxy alcohols 79-85 led to the formation of highly substituted 2,3-disubstituted tetrahydrofurans 80-86 stereoselectively. ... 

Sharpless and Masumune have applied the AE reaction on chiral allylic alcohols to prepare all 8 of the L-hexoses. ° AE reaction on allylic alcohol 52 provides the epoxy alcohol 53 in 92% yield and in >95% ee. Base catalyze Payne rearrangement followed by ring opening with phenyl thiolate provides diol 54. Protection of the diol is followed by oxidation of the sulfide to the sulfoxide via m-CPBA, Pummerer rearrangement to give the gm-acetoxy sulfide intermediate and finally reduction using Dibal to yield the desired aldehyde 56. Homer-Emmons olefination followed by reduction sets up the second substrate for the AE reaction. The AE reaction on optically active 57 is reagent... 

It is appropriate at this juncture to address some of the more useful transformations of 2,3-epoxy alcohols.913 A 2,3-epoxy alcohol such as compound 14 possesses two obvious electrophilic sites one at C-2, and the other at C-3. But in addition, C-l of a 2,3-epoxy alcohol also has latent electrophilic reactivity. For example, exposure of 14 to aqueous sodium hydroxide solution results in the formation of triol 19 in 79% yield (see Scheme 5). In this interesting transformation, hydroxide ion induces the establishment of an equilibrium between 2,3-epoxy-l-ol 14 and the isomeric 1,2-epoxy-3-ol 18. This reversible, base-induced epoxide migration reaction is a process known as the Payne rearrangement.14... 

As well as the Payne rearrangement, 2,3-epoxy alcohols and some of their derivatives show some other interesting rearrangement procedures that often constitute key steps in syntheses of complex molecules. 

Payne rearrangement. The Payne rearrangement2 of a primary cts-2,3-epoxy alcohol to a secondary 1,2-epoxy alcohol usually requires a basic aqueous medium, but it can be effected with BuLi in THF, particularly when catalyzed by lithium salts. As a consequence, the rearrangement becomes a useful extension of the Sharpless epoxidation, with both epoxides available for nucleophilic substitutions. Thus the more reactive rearranged epoxide can be trapped in situ by various organometallic nucleophiles. Cuprates of the type RCu(CN)Li are particularly effective for this purpose, and provide syn-diols (3).3... 

Asymmetric epoxidation of 10a under standard conditions yields the crystalline epoxy alcohol 2a in 95% ee (91% chemical yield). Treatment of 9a with thioanisol in 0.5N NaOH, in rerf-butyl alcohol solution, gives -after protection of the hydroxyl groups as benzyl ethers- the sulfide a (60% overall yield) through an epoxide ringopening process involving a Payne rearrangement. Since the sulfide could not be hydrolysed to the aldehyde 7a without epimerisation at the a-position, it was acetoxylated in 71% yield under the conditions shown in the synthetic sequence (8a... 

Epoxy-3-alcohols can be derived from 2,3-epoxy-1-alcohols by the base-catalyzed Payne rearrangement as illustrated in step d of Figure 6A.4 [59,64], The rearrangement is completely stereospecific but, because it is reversible, it usually results in an equilibrium mixture of the two epoxy alcohols for which the relative proportions are structure-dependent. Practical synthetic applications of this rearrangement therefore depend on methods that will shift the equilibrium completely in the direction desired. Nucleophiles such as thiolates and amines are... 

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