Rearrangements Payne rearrangement

Bnl, NaH, rt, 90% yield." Note that in this case the reaction proceeds without complication of the Payne rearrangement. 

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... 

Aza-Payne rearrangement of optically active A-aryl(alkyl)sulfonyl-substituted 2-aziridinemethanols to corresponding epoxysulfonamides 98CSR145. 

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... 

Scheme 5. Payne rearrangement/epoxide opening reaction hydroxide nucleophile.

A careful analysis of this problem led to the identification of an exceedingly simple solution (see Scheme 10). The Masamune-Sharpless solution to the threo 2,3-diol problem actually takes advantage of the ready availability of the erythro 2,3-diol diastereoisomer. As we have seen in Scheme 9, erythro 2,3-diols such as 20 can be conveniently assembled from trans allylic alcohols via sequential SAE and Payne rearrangement/epoxide opening reac-... 

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. 

Scheme 9.9 a) SAE on dienols. b) Payne rearrangement, resulting in byproducts. 

The epoxidation of divinyl carbinol constitutes a special case of a dienol epoxida-tion, as the starting diene is not conjugated (Scheme 9.10). Desymmetrization by SAE, followed by a Payne rearrangement, furnishes the vinylepoxide in high yield and with excellent enantioselectivity (compare Table 9.2, Entry 1) [43]. 

In the Payne rearrangement, a 2,3-epoxy alcohol is converted to an isomeric one, by treatment with aqueous base ... 

Aziridines from Amino Epoxides by a Modified Payne Rearrangement... 

A modified Payne rearrangement of amino epoxides catalyzed by Lewis acid or induced by base, represents an interesting but a limited method for the synthesis of fonctionalized aziridines of high enantiopurity. The limitations are primarily due to the accessibility of the starting materials (Scheme 6) [15]. 

R,8S)-(+)-Disparlure (12) is the female sex pheromone of the gypsy moth (Lymantria dispar). Advent of Sharpless asymmetric dihydroxylation (AD) allowed several new syntheses of 12 possible. Sharpless synthesized 12 as shown in Scheme 17 [27]. Scheme 18 summarizes Ko s synthesis of 12 employing AD-mix-a [28]. He extended the carbon chain of A by Payne rearrangement followed by alkylation of an alkynide anion with the resulting epoxide to give B. Keinan developed another AD-based synthesis of 12 as shown in Scheme 19 [29]. Mit-sunobu inversion of A to give B was the key step, and the diol C could be purified by recrystallization. 

An alternative synthesis producing a chiral-substituted 3-azoniaspirooctane, 153 has been published by Liu and co-workers where a modification of the Payne rearrangement was applied to amine epoxide 152 (Equation 35) <1997JCS(P1)511>. 

Thus far, we have discussed nucleophilic ring opening in 2,3-epoxy-l-ol taking place at the C-2 and C-3 positions (see compound 58 in Scheme 4-19). However, in the presence of a base, nucleophilic ring opening can take place at C-l via Payne rearrangement to produce 2,3-diol.36 For example, compound 1,2-... 

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