Anti-1,3-diol monoester

A syn-2-amino alcohol, complexed with Yb(III), catalyses the aldol-Tishchenko reaction of aliphatic ketones with aromatic aldehydes to give anti- 1,3-diol monoesters with three adjacent stereocentres in high yield, de, and ee.141 ... 

Evans, D. A., Hoveyda, A. H. Samarium-catalyzed intramolecular Tishchenko reduction of 3-hydroxy ketones. A stereoselective approach to the synthesis of differentiated anti 1,3-diol monoesters. J. Am. Chem. Soc. 1990, 112, 6447-6449. 

Amongst this class of reactions, the Sml2-catalysed intramolecular Tishchenko reaction developed by Evans and Hoveyda has found widespread application.39 In this transformation, excess aldehyde is used with a sub-stoichiometric amount of Sml2 to convert (3-hydroxy ketones into anti-diol monoesters in high yield and high diastereomeric excess (Scheme 7.8). 

The mixed Tishchenko reaction involves the reaction of the aldol prodnct 113 from one aldehyde with another aldehyde having no a-hydrogens to yield an ester The products were proposed to be formed through an aldol step (equation 33), followed by addition of another aldehyde (equation 34) and an intramolecular hydride transfer (equation 35). However, several aspects of this mechanism need to be clarified. As part of the continuing mechanistic studies carried out by Streitwieser and coworkers on reactions of alkali enolates ", it was found that the aldol-Tishchenko reaction between certain lithium eno-lates and benzaldehyde proceeded cleanly in thf at room temperature". Reaction of the lithium enolate of isobutyrophenone (Liibp) with 1 equiv of benzaldehyde in thf at — 65 °C affords a convenient route to the normal aldol product 113 (R = R" = Ph, R = Me). At room temperature, however, the only product observed after acid workup was the diol-monoester 116, apparently derived from the corresponding lithium ester alcoholate (115, R = R" = Ph, R = Me), which was quantitatively transformed into 116 after quenching. As found in other systems", only the anti diol-monoester diastereomer was formed. 

A stereoselective Tischenko reduction of P-hydroxyketones in the presence of a catalytic amount of Sc(OTf)3 has been described [155]. Aliphatic and aromatic substrates were reduced to 1,3-diol monoesters in moderate to high yields (38-93%) with high 1,3-anti diastereoselectivities (de = 76- > 95%). 

The excellent level of anti selectivity in the formation of the 1,3-diol monoester can be explained by transition state A shown in Scheme 9.1. 

Alkenes may also react with certain oxidizing agents to result in anti hydroxyla-tion. Treatment with peroxycarboxylic acids435 leads initially to an epoxide. Ring scission of the latter via an SN2 reaction in an anti manner with the corresponding carboxylic acid or water gives the trans monoester or tram diol, respectively. Complete anti stereoselectivity and high yields in the oxidation of cycloalkenes are... 

Anti hydroxylation of an alkene is readily achieved with peroxycarboxylic adds. Add-catalyzed ring opening of the irutial produd, an oxirane (epoxide), forms the monoester of a 1,2-diol, hydrolysis of which affords the parent diol. Alternative reagents whi ate often used for anti hydroxylation of alkenes are hydrogen peroxide with oxides of tungsten > 4.2i gj. selenium, 444i and iodine-silver benzoate (Pr6vost reaction).. ... 

Rhizoxin D, a natural product possessing potent antitumor and antifungal activity, was synthesized by J.W. Leahy and co-workers. " To establish the C17 stereocenter, they utilized the Evans-Tishchenko reaction. To this end, the 3-hydroxyketone substrate was reacted with p-nitrobenzaldehyde in the presence of catalytic Smb. The reaction yielded the monoester of the anti 1,3-diol as a single product. 

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