Enantioselective synthesis of protected α-hydroxy aldehydes and ketones via hydroxylation of metalated chiral hydrazones

✍ Scribed by Dieter Enders; Vidya Bhushan

• Publisher: Elsevier Science
• Year: 1988
• Tongue: French
• Weight: 282 KB
• Volume: 29
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)87901-0

✦ Synopsis

a-Benzyloxy aldehydes and a-acetoxy ketones 4 of high enantiomeric purity are prepared in good overall yields via oxaziridine mediated hydroxylation of chiral hydrazone azaenolates. As auxiliaries novel proline derived hydrazine reagents 5 are used.

The importance of a-hydroxy carbonyl compounds as crucial structural features of many natural products and as chiral building blocks initiated numerous studies for their stereoselective synthesis'.

An attractive route to this versatile class of compounds is the direct oxidation of the parent carbonyl compounds and their enolates' or enol derivativess. Consequently, overall enantioselective procedures using this approach have been developed recently4. With one exeption4f, all of these new techniques lead to a-hydroxy acid derivatives. Thus, the efficient a-hydroxylation of simple aldehydes and ketones affording protected a-hydroxy synthons of type A and B remains to be solved.