Michael-Type Reactions between Electron-Deficient 1,3-Dienes and Dimethylgermylene/Water

✍ Scribed by Wienken, Stefan ;Neumann, Wilhelm P.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1993
• Tongue: English
• Weight: 537 KB
• Volume: 126
• Category: Article
• ISSN: 0009-2940
• DOI: 10.1002/cber.19931260330

✦ Synopsis

Abstract

A new type of reaction between dimethylgermylene (Me~2~Ge) (1), generated in situ from a 7‐germanobornadiene, and electron‐deficient 1,3‐dienes RR′CCH – CHCH – Z [ZC(O)Me, CO~2~R″ 2a – f] or cyclic dienones 8, 9 in the presence of water is described. The Michael‐type behaviour of the system Me~2~Ge/H~2~O is clearly shown by the nucleophilic addition to the unsaturated systems resulting in the formation of β1‐ and δ1‐adducts, the new allylgermanes 3a – g, 4a –c, 10a, b, 11. The cis configuration of the resulting double bond of the δ adducts 4a–c is remarkable. With open‐chain dienes cycloaddition of 1 without participation of water, yielding germacyclopentenes 5a, b or germacyclopentanes 7a, b, competes with the Michael‐type reaction. A slight variation of the substitution pattern of the dienes has a strong influence on the reaction course.