Oxidants Davis’ oxaziridine

During the highly stereoselective total synthesis of epothilone B by J.D. White and co-workers, the stereochemistry of the alcohol portion of the macrolactone was established by applying Davis oxaziridine oxidation of a sodium enolate. The sodium enolate was generated from the corresponding chiral oxazolidinone derivative, which upon oxidation gave 71% yield of a-hydroxylated compound. 

Davis oxaziridine oxidation Oxidation of electron-rich substrates (e.g. alkenes, enolates, enol ethers etc.) with oxaziridines. 130... 

Related reactions Davis oxaziridine oxidation, Prilezhaev reaction, Sharpless asymmetric epoxidation, Shi asymmetric epoxidation ... 

The hydroxyl group in alcohol 122 is then oxidized. Deprotonation of this ketone with KHMDS (1 eq.), followed by the addition of Davis oxaziridine (see Chapter 4 for a-hydroxylation of ketones)28 (2 eq.) allows the stereo-controlled introduction of the C-10 oxygen from the less hindered enolate face, providing only the (i )-hydroxyketone 123. Subsequent reduction of 123 with excess LAH provides the tetra-ol 124. Treatment of this compound with imidazole and TBSC1 followed by PPTS and 2-methoxypropene provides in one operation the acetonide 125 with 91% yield (Scheme 7-37). 

Chiral Davis oxaziridines allow the oxidation of phosphonates to a-hydroxy-phosphonates in good ee with apparently wide generality and with a sense of induction that is well controlled by the chirality of the reagent used.109 mCPBA oxidation of a bi-cyclic e do-camphorylsulfonylimine surprisingly resulted in an exo-camphorylsulfonyl-oxaziridine, whereas all other camphorylsulfonylimines resulted only in endo-oxaziiidines.110 Asymmetric oxidation of sulfides to sulfoxides and the a-hydroxylation of enolates were predicted by models in which steric interactions are minimized. 

Davis oxaziridine c) MOMCI, f-Pr2NEt, CH2CI2 d) DIBAL-H e) Swern oxidation, f) PhjP-CHC02Me, CH2CI2 g) NaBH4, THF/ H2O h) TrCl, DMAP, CH2Cb i) NaH, Mel, DMF )) TBAF,THF k) CuBr SMe2, MeLi LiBr,... 

The first total synthesis of (-)-fumiquinazoline A and B was accomplished by B.B. Snider and co-workers using a Buchwald-Hartwig Pd-catalyzed cyclization of an iodoindole carbamate to construct the imidazoindolone moiety. In order to set up the stereochemistry at the benzylic position of the indole fragment, the double bond was oxidized with the saccharine-derived Davis oxaziridine in the presence of methanol to give the major diastereomer in 65% yield. 

The synthesis of the 4 -spiroannulated ribonucleoside was aceomplished by elimination of the 2 -phenylthio group of compound 132 via a controlled oxidation with Davis oxaziridine reagent. 

Davis and coworkers [506, 744] performed the asymmetric oxidation of pro-chiral sulfides with chiral oxaziridines, and reagents bearing the bomane skeleton 2.82 or 2.83 (X = Cl) were the most efficient. The chiral oxaziridine oxidations are... 

Davis oxaziridine reagents such as 1 have exhibited ample synthetic utility as oxidizing agents for the hydroxylation of enolates to provide a-hydroxy carbonyl compounds, such as 2 with superb yield. When the oxaziridine is chiral and nonracemic, the hydroxylation has been shown to proceed with high stereoselectivity.1... 

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