Sharpless asymmetric rearrangement

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. 

Aryl and alkenyl groups undergo this anft -migration more easily than an alkyl group. This rearrangement in combination with Sharpless asymmetric epoxidation affords a stereocontrolled route to aldols and 1,3-diols (second example). 

The MABR-promoted rearrangement, when applied to optically active epoxy substrates, has been shown to proceed with rigorous transfer of the epoxide chirality. Accordingly, used in combination with the Sharpless asymmetric epoxidation of allylic alcohols,5 this rearrangement represents a new approach to the synthesis of various... 

Aldol products do not have to come from an aldol condensation. In another example of catalysis by a small organic molecule, Jeffrey Bode of UC Santa Barbara reports (J- Am. Chem. Soc. 2004,126, 8126) that the thioazolium salt 7 effects the rearrangement of an epoxy aldehyde such as 6 to the aldol product 8. This is a net oxidation of the aldehyde, and reduction of the epoxide. As epoxy aldehydes such as 6 are readily available by Sharpless asymmetric epoxidation, this should be a general route to enantiomerically-aldol products. The rearrangement also works with an aziridine aldehyde such as 9, to give the ff-amino ester 10. 

SHAFIPLESS Asymmetne epoxidation 343 SHARPLESS Asymmetric d tydroxylalion 344 SHERAOSKY Rearrangement 345 SHESTAKOV Hydrazine synthesis 346 SIEGRIST Stilbene synthesis 347 SIMMONS - SMITH Cydopropane synthesis 348... 

Allyl epoxides are produced by the acclaimed Sharpless asymmetric epoxidation reaction [75], and are important intermediates and products. For example, an allyl epoxide is a vital part of the structure of amphidinolides, a series of unique macrolides isolated from dinoflagellates (Amphidinium sp.). Amphidinolide H (AmpH) is a potent cytotoxic 26-membered macrolide with potent cytotoxicity for several carcinoma cell lines [76]. An allyl epoxide is involved in the total synthesis of prostaglandin A2 with a cuprate reagent [77]. Allyl epoxides derived from Sharpless chemistry are a practical method for construction of polypropionate structures by Lewis acid-induced rearrangement [78,79]. Other allyl epoxides such as l,2-epoxy-3-methyl-3-butanol are useful organic intermediates for the production of a-hydroxyketones, which are used for the synthesis of various natural... 

In their short synthesis of ( - )-162, Pearson and Hembre also began with the protected D-erythronolactone derivative 197, which was converted in three steps into a mixture (97 3) of diastereomeric allylic alcohols 203 (Scheme 29) 127). Separation of the epimers, although possible, was not necessary as both alcohols yielded the same product 204 after Johnson orthoester Claisen rearrangement. Subsequent Sharpless asymmetric dihydroxylation with AD-Mix-p gave as major... 

Introduction Catalytic methods of asymmetric induction Part I - Sharpless Asymmetric Epoxidation The AE Method The ligands The catalyst Catalyst structure The mnemonic device The synthesis of propranolol Modification after Sharpless Epoxidation Oxidation after Sharpless epoxidation The Payne rearrangement... 

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