Evans rearrangement

Conversion of allylic alcohols to allylic suifoxides and aiiyiic suifoxides to aiiyiic aicohois (Evans, 1971)  

The first asymmetric total synthesis of the macrocyclic lactone metabolite (+)-pyrenolide D was accomplished in the laboratory of D.Y. Gin. The natural product has a densely functionalized polycyclic structure and its absolute configuration had to be established. The key step of the synthesis was a stereoselective oxidative ring-contraction of a 6-deoxy-D-gulal, which was prepared from anomeric allylic sulfoxide via the Mislow-Evans rearrangement. 

In the stereoselective total synthesis of ( )-14-deoxyisoamijiol by G. Majetich et al., the last step was the epimerization of the C2 secondary allylic alcohol functionality. The Mitsunobu reaction resulted only in a poor yield (30%) of the inverted product, so the well-established sulfoxide-sulfenate rearrangement was utilized. The allyic alcohol was first treated with benzenesulfenyl chloride, which afforded the thermodynamically more stable epimeric sulfenate ester via an allylic sulfoxide intermediate. The addition of trimethyl phosphite shifted the equilibrium to the right by consuming the desired epimeric sulfenate ester and produced the natural product. 

The Mislow-Evans rearrangement was chosen by T. Tanaka and co-workers to create the C12 stereocenter of halicholactone and ensure the ( ) stereochemistry of the C9-C11 double bond.  

R = alkyl, aryl, heteroaryl, alkenyl H-Nuc 0-, S-, N- and C-nucleophlles R = C02Et (DEAD), C02/-Pr (DIAD), CON(CH2)5 (ADDP), CONMe2 (TMAD) Y = alkyl, aryl, heteroaryl, 0-alkyl solvent THE, dioxane, DCM, CHCI3, DMF, toluene, benzene, HMPA R = H, CH3, Ph, 4-NO2C6H4, 3,5-(N02)2C6H3, alkyl, aryl R = alkyl, aryl, heteroaryl X = O, S Z Z = CO-alkyl, CO-aryl, C02-alkyl, C02-aryl, ON 

Masaki, Y. Sakuma, K. Kaji, K. Chem. Pharm. Bull. 1985, 33, 2531. 

Sn2 inversion of an alcohol by a nucleophile using diethyl azodicarboxylate (DEAD) and triphenylphosphine. 

Palladium-catalyzed reaction of aryl halides with diboron reagent to produce aryl-boronates. Also known as Hosomi-Miyaura borylation. 

Takahashi, K. Takagi, J. Ishiyama, T. Miyaura, N. Chem. Lett. 2000, 126. 

Oxidation of alcohols using DCC and DMSO, also known as Pfitzner-Moffatt oxidation . 

Name Reactions, 4Hi ed., DOI 10.1007/978-3-642-01053-8 164, Springer-Verlag Berlin Heidelberg 2009 

Christen, D. P. Mitsunobu reaction. In Name Reactions for Homologations-Part // Li, J. J., Corey, E. J., Eds. Wiley Sons Hoboken, NJ, 2009, pp 671-748. (Review). 

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 177, Springer International Publishing Switzerland 2014 

Brebion, F. Najera, F. Delouvrie, B. Lacote, E. Fensterbank, L. Malacria, M. Synthesis 2007, 2273-2278. 

Cevallos, A. Rios, R. Moyano, A. Pericas, M. A. Riera, A. Tetrahedron Asymmetry 2000,11,4407-A416. 

---

Mislow-Evans Rearrangement (Evans (-Mislow) Rearrangement)... 

Treatment of l-chloro-2-methylalkenyl p-tolyl sulfoxides with AMithio-2-pipcrid-one in THF at room temperature resulted in the formation of l-chloro-2-(hydroxy-methyl)alkenyl p-lolyl sulfides in good yields. The reaction is the first example of the Mislow-Braverman-Evans rearrangement retaining the sulfur atom on the original carbon.29... 

The other major [2,3]-rearrangement, the Evans rearrangement,463 can be extended to synthesize functionalized allyl alcohols.464-465 The Evans rearrangement involves the rearrangement of an allylic sulfoxide to an allyl alcohol.463 The reverse reaction is also possible the conversion of an allyl alcohol to the analogous sulfoxide. The push-pull nature of the two rearrangements (Scheme 26.19), coupled with the transfer of chirality, provides a method to invert an allyl alcohol together with the isomerization of the alkene (Scheme 26.20)438,466... 

The Evans rearrangement can be driven to completion by the addition of a thiophile, such as trimethylphosphite (Scheme 26.19) 440 46 M This strategy allows the chemistry of the allyl phenyl sulfoxide, or other sulfur precursor, to be exploited before the allyl alcohol is unmasked.4 3 471 474 The addition of phenylsulfenyl chloride to an alkene, followed by the elimination of hydrogen chloride and subsequent rearrangement, provides a useful synthesis of allyl alcohols.473 475 The [2,3]-Evans sigmatropic rearrangement is concerted and allows for stereochemical transfer.476 477 The reverse reaction, formation of the allyl sulfoxide, results from the treatment of an allyl alcohol using a base followed by arylsulfenyl chloride to produce the allyl sulfoxide.478 479... 

Scheme 42 Discovery of the Type K (Mislow-Evans) rearrangement...

Scheme 46 Deprenylation of lipopeptides by application of the Mislow-Evans rearrangement...

In a series of pubhcations Warren et al. demonstrated the usefulness of 1,3-chirality transfer in the context of Type M rearrangements to synthesize 1,4,5-stereo triads with -configured double bonds (Scheme 90) [209-211]. Based on their successful work on diol syntheses with 1,4-related stereogenic centers across E-configured double bonds [212,213] involving the Mislow-Evans rearrangement (Sect. 3.5), the authors developed a procedure for the stereoselective synthesis of E-homoallyhc sulfides. 

In the diterpene series a notable recent example of semisynthesis is that (ref.24) of pachiclavularolide (28) a substance isolated from the soft coral, Pachiclavularia violacea. starting from S-citronellal readily available from S-citronellol. The key step in the formation of the macrocycle is an intramolecular palladium-catalysed diyne cyclisation following initially a Mislow-Evans rearrangement of a sulphinyl ester from S-citronellal. ... 

During the final stages of the total synthesis of (-)-subergorgic acid by L.A. Paquette and co-workers, the transposition of a tricyclic enone was needed. The enone was exposed to the Luche conditions and an 85 15 mixture of diastereomers was obtained. In order to achieve this level of diastereoselectivity, the reaction temperature had to be lowered to -50 °C instead of the usual 0 °C. The major product was formed via the exo attack of the carbonyl group by the hydride. The allylic alcohol was later converted to the corresponding sulfoxide followed by a Mislow-Evans rearrangement to the isomeric allylic alcohol. 

Masaki, Y., Sakuma, K., Kaji, K. Facile synthesis of (E)-allylic alcohols by acid-catalyzed modification of the Mislow-Evans rearrangement of allylic sulfoxides. Chem. Pharm. Bull. 1985, 33, 2531-2534. 

Jones-Hertzog, D. K., Jorgensen, W. L. Regioselective Synthesis of Allylic Alcohols Using the Mislow-Evans Rearrangement A Theoretical Rationalization. J. Org. Chem. 1995, 60, 6682-6683. 

The other major [2,3]-rearrangement, the Evans rearrangement [448], can be extended to synthesize functionalized allyl alcohols [449,450], The Evans re-... 

---