Highly stereoselective syntheses of spiroacetal enol ethers, (E)- and (Z)-methoxycarbonylmethylene-1, 6-dioxaspiro[4.5]decanes

✍ Scribed by Hiroaki Toshima; Hisateru Aramaki; Furumoto Yoshinori; Shintaro Inamura; Akitami Ichihara

• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 849 KB
• Volume: 54
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(98)00241-5

✦ Synopsis

E)-and (Z)-2-methoxyca_rbonylmethylene-l,6-dioxaspiro[4.5]decanes have been synthesized from an aeydie keto alcohol possessing an alkynoate past via intr, maoleculat conjugate addition. Unde~ thermodynamically controlled conditions using t-BuOK in THF, the (E)-isomer could be obtained in 52:1 ratio. When a catalytic mtount of Pd(OAe)2 was used in benzene, the (Z)isomer could be obtained in 95:1 ratio.