Facial-selective allylation of methyl ketones for the asymmetric synthesis of alpha-substituted tertiary homoallylic ethers
Tietze, LF; Volkel, L; Wulff, C; Weigand, B; Bittner, C; Mcgrath, P; Johnson, K; Schafer, M
| HERO ID | 5410444 |
|---|---|
| In Press | No |
| Year | 2001 |
| Title | Facial-selective allylation of methyl ketones for the asymmetric synthesis of alpha-substituted tertiary homoallylic ethers |
| Authors | Tietze, LF; Volkel, L; Wulff, C; Weigand, B; Bittner, C; Mcgrath, P; Johnson, K; Schafer, M |
| Journal | Chemistry: A European Journal |
| Volume | 7 |
| Issue | 6 |
| Page Numbers | 1304-1308 |
| Abstract | The asymmetric synthesis of enantiomerically pure a-substituted tertiary homoallylic ethers 4a, 11 and 12a-c by the allylation of ethyl methyl ketone (la) with gamma-substituted allylsilanes 9a-h is described. The allylsilanes were obtained by a nickel-catalysed Grignard cross-coupling reaction of (E)- and (Z)-(3-iodoallyl)trimethylsilane with various Grignard reagents. The reaction of the allylsilanes with la in the presence of the trimethylsilyl ether of N-trifluoroacetylnorpseudoephedrine (3), and catalytic amounts of a mixture of trimethylsilyl triflate and trifluoromethanesulfonic acid led to the homoallylic ethers 4a, 11 and 12a-c with two new stereogenic centres, with a selectivity of 1:9 to >20:1 for the homoallylic and of 1:99 to >60:1 for the allylic centre. The facial selectivity does not depend on the configuration of the allylsilane, and in all reactions the anti product is preferentially formed. Interestingly, a pronounced switch of facial selectivity takes place with increasing length of the alkyl group of the allylsilane. |
| Doi | 10.1002/1521-3765(20010316)7:6<1304::AID-CHEM1304>3.0.CO;2-9 |
| Pmid | 11322558 |
| Wosid | WOS:000167744300019 |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |
| Language Text | English |
| Keyword | allylation; amino alcohols; homoallylic alcohols; silanes |