Highly efficient and stereoselective route to threo- and erythro-α-allylated α-fluoro-β-hydroxy esters via radical allylation reaction

✍ Scribed by Takashi Ishihara; Kazuhide Mima; Tsutomu Konno; Hiroki Yamanaka

• Publisher: Elsevier Science
• Year: 2002
• Tongue: French
• Weight: 92 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)00608-1

✦ Synopsis

Treatment of a-bromo-a-fluoro-b-hydroxy esters with trimethylaluminum in dichloromethane, followed by reaction with allylic stannanes and a catalytic amount of triethylborane at -15°C, gave the corresponding threo-a-allylated a-fluoro-bhydroxy esters in a highly stereoselective manner. On the other hand, the reaction of the b-hydroxy esters with allylic stannanes under the influence of a catalytic amount of triethylborane in tetrahydrofuran or isopropyl alcohol at -78°C proceeded erythro-selectively, leading preferentially to the erythro-isomers of the corresponding a-allylated esters.