Studies in macrolide synthesis: a synthesis of two chiral fragments of oleandomycin and lankamycin.
โ Scribed by Ian Peterson
- Publisher
- Elsevier Science
- Year
- 1983
- Tongue
- French
- Weight
- 245 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0040-4039
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โฆ Synopsis
swrrmary: A synthesis of the two structurally-related chiral oleandomycin and lankamycin is described.
๐ SIMILAR VOLUMES
The (9s)-macrolide 1 (P = TBS) was prepared in 14 steps (5% yield) with 63% overall ds starting from the ethyl ketone ($2. The Cl-C7 and Q-C13 segments, 3 and 4, were obtained via boron enolate aldol reactions mediated by (+)-and (-)-(Ipc)zBOTf, respectively. Conventional reduction conditions using
A/do/ condensation of chiraal ethylketones 8 and 9,via their 9-BBN or "BupB eno/ates,with methacrolein and acetaldehyde gives mainly the &&&I adduct, 8 -+ 14 or 9 + 18. The chiral reagent (+)-(lpc)~OTf, in the presence of EL& is used to enhance the formation of 14 and 78, while
The Ct-Ct3 segment 6 of concanamycin A (1) was prepared by a highly stereocontrolled route (87% overall ds) in 16 steps from the ester 9. Key steps are the one-pot aldol/reduction, 8 + 12, and the HWB reaction, 18 + 19 + 6.8 1997 Elsevier Science Ltd.