Herstellung von erythro-2-Hydroxybernsteinsäure-Derivaten aus Äpfelsäureester. Vorläufige Mitteilung
✍ Scribed by Dieter Seebach; Daniel Wasmuth
- Publisher
- John Wiley and Sons
- Year
- 1980
- Tongue
- German
- Weight
- 202 KB
- Volume
- 63
- Category
- Article
- ISSN
- 0018-019X
No coin nor oath required. For personal study only.
✦ Synopsis
Preparation for erythro‐2‐Hydroxy‐succinic Acid Derivatives from Malic Esters
As a contribution to the much discussed diastereoselective synthesis of enantiomers of open chain compounds, > 90% erythro‐selective branching of malic esters by alkylation of the doubly deprotonated derivative 2 (alkoxide‐enolate) with methyl, allyl, and benzyl halides in THF at −78° (→ 3aa, 3ba, 3bb, 3bc, Table 1) is described. A second alkylation (→ 4) and addition of 2 to acetone (→ 5) are also possible. Cyclization of 2 to the enantiomerically pure trans‐epoxides 6 is achieved by treatment with iodine. Cuprate opening of 6b furnishes the same product 3ba obtained from the methylation of 2b, establishing the configurational assignment.