You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via5.1.26.5 Method 5: Selective χ-Alkylation of Germanium-Masked Dienolates
Please login to access the full content or check if you have access via
Spivey, A. C.; Diaper, C. M., Science of Synthesis, (2003) 5, 185.
Lewis acid promoted nucleophilic addition of allylic group 14 metals to aldehydes,[37,65,66] aldimines,[67,68] α-alkoxystannanes,[69] thioacetals,[70] and acetals[71–73] has become a powerful tool for C—C bond formation in modern organic synthesis as has the reaction with an alcohol in the presence of iodosobenzene for the formation of allyl ethers.[74,75] Although allylgermanes participate in these transformations, their use rarely offers any significant advantage from a synthetic standpoint over the more economically attractive silyl or stannane analogues except for the markedly lower toxicity of organogermanes relative to organostannanes.[76] However, allylgermanes have proved particularly useful in addressing the problem of selective C—C bond formation at the χ-position of dienolates.[77] Trapping lithium dienolate 23 [generated from ethyl 3-methylbut-2-enoate (22) and lithium diisopropylamide] with silyl, germyl, and stannyl halides results in regioselective O- 24, α-C 25, and χ-C 26 trapping respectively (Scheme 7).[78]
Meeeee 8 Meeeeeee ee Meeeeeeeee eeee Meeee 88 Meeeeeee[88]
Mee eeeeeeeee eeeeee eeeeeeeee 88 eeeeee eeeeeeeeeeeeeeee ee eee χ-eeeeeeee eeee eeeeeeeeeeeee eeee ee eeeeeee,[88] eeeeeee eeeeeeeeeeeeeeee,[88] eeeeeeeee,[88] eeeee eeeeeee,[88] ee Meeeeee eeeeeeeee[88] eeee Meeee eeee eeeeeeeeee ee eeeeeee e eeeee ee eeeeeeeeeeeee eeeeee eeeeeeeeeeeee 88 (Meeeee 8). Meeeeee eee ee eeee eeeeeeeeeeeee–eeeeeeeeee eeeeeeee eee ee eeee ee eeeeeeeee eee Meeee eeee eeee eeeeeeeeeeeeeeeeee eeeeeeee, eeeee eeeeeee ee eeeeeeeee α-eeeeeeeeee ee eee eeeeeeeee-eeeeee eeeeeeeee eeee Meeeeee eeeeeeeee.[88]
Meeeee 8 Meeeeeeee ee eee χ-Meeeeeee ee e Meeeeeeee-Meeeee Meeeeeeee[88,88,88]
| Meeeeeeeeeee | M | Meeee Meee | Meeeeeeeee | Meeee (M/M) | Meeee (%) | Mee |
|---|---|---|---|---|---|---|
| MeMM(MMe)8 | MM(MMe)Me | MeMe8 | −88 ee −88°M, 8 e | 8.8:8 | 88 | [88] |
| MeMMM | MM(MM)Me | MeMe8 | −88°M, 8 e | 8.8:8 | 88 | [88] |
| MeMM=MMMM8Me | MM8MM=MMMe | MMMMe | ee, 88 eeee, 88 e | 8.8:8 | 88 | [88] |
| MMMM | M(MM8Me)MM(MM8Me) | MeMe8 | −88°M ee ee, 8 e | 8:8 | 88 | [88] |
| MeMM=M(MM8Me)8 | MMMeMM(MM8Me)8 | MeMe8 | −88°M ee ee, | 8.8:8 | 88 | [88] |
References
| [37] | Meee, M.; Meeeeeee, M.; Meeeeee, M.; Meee, M., Meeeeeeee, (8888), 888. |
| [65] | Meeeeee, M.; Meee, M., Meeeeeeeeee Meee., (8888) 88, 888. |
| [66] | Meee, M.; Meeeeeeee, M.; Meeee, M.; Meeee, M.; Meeeee, M., Meeeeeeeeeeeeee, (8888) 88, 8888. |
| [67] | Meeeeee, M.; Meee, M.; Meeee, M.; Meeeeeeee, M., Meee. Meeeee. (Meeeeeeee), (8888), 8888. |
| [68] | Meeeeee, M.; Meee, M., Meeeeee, (8888), 888. |
| [69] | Meeeeeee, M.; Meeeeee, M.-e., M. Mee. Meee., (8888) 88, 8888. |
| [70] | Meee, M.; Meeee, M.; Meeeee, M., M. Mee. Meee., (8888) 88, 8888. |
| [71] | Meeeee, M.; Meeee, M.; Meeeeeee, M., M. Meee. Mee., Meee. Meeeee., (8888), 8888. |
| [72] | Meeeee, M.; Meeeeeeee, M.; Meeeee, M.; Meeeeeee, M., Meeeeee, (8888), 888. |
| [73] | Meeeeee, M. M.; Meeeeeee, M. M., M. Mee. Meee., (8888) 88, 8888. |
| [74] | Meeeee, M.; Meeeee, M.; Meeeeee, M.; Meeeeeeee, M., Meeeeeeeeee Meee., (8888) 88, 888. |
| [75] | Meeeee, M.; Meeeee, M.; Meeeeee, M.; Meeeeeeee, M., Meee. Meeee. Meee., (8888) 88, 888. |
| [76] | Meeeeeee, M.; Meeeeeeeee, M. M., Me Mee Meeeeeeee ee Meeeeee Meeeeeeee, Mee eee Meee Meeeeeeee, Meeee, M., Me.; Meeee: Meeeeeeeee, (8888), ee 888–888. |
| [77] | Meeeeeee, M.; Meee, M., Meee. Mee., (8888) 88, 8888. |
| [78] | Meeeeeee, M.; Meeeeee, M.; Meeeee, M., M. Mee. Meee., (8888) 88, 8888. |
| [79] | Meeeeeee, M.; Meeeeee, M.; Meeeee, M., M. Meee. Mee., Meee. Meeeee., (8888), 8888. |
| [80] | Meeeeeee, M.; Meeeeee, M.; Meeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
| [81] | Meeeeeee, M.; Meeee, M.; Meeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) 88/8, 88.
Return to Top