Fluorinated Analogs of Retinoids: Stereocontrolled Synthesis Employing Fluoroisoprenoidal Horner Ylides
✍ Scribed by Heng-xu Wei; Manfred Schlosser
- Book ID
- 101277289
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 184 KB
- Volume
- 1998
- Category
- Article
- ISSN
- 1434-193X
No coin nor oath required. For personal study only.
✦ Synopsis
An improved method for the preparation of ethyl 2-fluoro-3-the ester tail. Thus, Horner-Wittig reactions accomplished with benzaldehyde and (Z)-or (E)-(β-ionylidene)-acet-methyl-2-butenoate (3) is described. The two stereoisomers [(E)-4 and (Z)-4] obtained after γ-bromination can be aldehyde lead inevitably to stereorandomization at the terminal, ethoxycarbonyl-bearing double bond affording (E)-separated and can be individually converted into the corresponding diethyl phosphonates. The PO-ylides and (Z)-isomers in 50:50 to 15:85 ratios, depending on the reaction conditions. The new double bond, however, is generated by α-deprotonation of the latter lose their stereochemical integrity by rapid torsional equilibration of formed with perfect trans-selectivity.