Payne epoxidation

MCPBA is the reagent most commonly used for alkene epoxidation. Payne oxidation (H O / CUjCN) is a convenient and inexpensive alternative. In the course of a study of the enantioselective enzymatic hydrolysis of 6, Takeshi Sugai of Keio University has described Tetrahedron Lett. 2007, 48, 979) a practical procedure for multigram Payne epoxidation of 5. 

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-... 

With regard to the use of tungsten-based systems, Payne and Williams reported on the selective epoxidation of maleic, fumaric, and crotonic acids with a catalytic amount of sodium tungstate (2mol%) in combination with aqueous hydrogen... 

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]. 

The Payne epoxidation with benzonitrile/ hydrogen peroxide is also an efficient epoxidation process. It is often the method of choice for industrial batch-type applications, but on a small scale the need for continuous pH control is inconvenient. 

Aziridines from Amino Epoxides by a Modified Payne... 

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>. 

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... 

This Payne rearrangement of an optically active epoxide (4) was used for a synthesis of pure (+ )-exo-brevicomin (6) in 31% overall yield. 

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... 

Passerini Reaction, 65, 1 Pauson-Khand reaction to prepare cyclopentenones, 40, 1 Payne rearrangement, 60, 1 Pechmann reaction, 7, 1 Peptides, synthesis of, 3, 5 12, 4 Peracids, epoxidation and hydroxylation with, 7, 7... 

If a polyol with a primary epoxide is treated with strong base, a rearrangement to the more stable secondary epoxide takes place, as observed by Payne [40]. If an unprotected bromodeoxyaldonolactone is treated with strong base a similar rearrangement may be expected. We found that if 6-bromo-2,6-dideoxy-D-arahzno-hexonolactone (3) (Scheme 5) was treated with 4 molar equivalents of potassium hydroxide, 2-deoxy-L-n bo-hexono-1,4-lactone (15) was isolated as the only product after work up [32]. 

Further progress in the use of ler -butyl hydroperoxide was made recently by Payne.1SlB -who conducted the reaction under carefully controlled pH conditions. Qimemaldhbyde, which had previously failed to yield the desired epoxide with alkaline hydrogen peroxide, gave this substance in good yield (Eq 81) when the reaction was tarried out at pll 8.C in methanol. 

Unusual triethylamine-catalysed rearrangements of bicyclic endoperoxides derived from substituted cycloheptatrienes have produced383 a variety of products (see, e.g., Scheme 80). Ab initio calculations have shown that energised 2,3-epoxypropoxide anions undergo a degenerate Payne rearrangement in the gas phase via a three-centre mechanism.384 It has been reported385 that treatment of isonitrile epoxides (330) with... 

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