Enantioselective aldol chemistry via alkyl enol ethers. Scope of the Lewis acid catalyzed condensation of optically active trimethylsilyl and methyl 2-[(E)-1-alkenyloxy]ethanoates with acetals
作者:James A. Faunce、Bryan A. Grisso、Peter B. Mackenzie
DOI:10.1021/ja00009a029
日期:1991.4
Optically active, mono- and disubstituted trimethylsilyl 2-[(E)-1-alkenyloxy]ethanoates of the type RR 1 CH=CHOCHR 2 CO 2 SiMe 3 (R=Me, PhCH 2 , n-Bu, MeO 2 CCMe 2 CH 2 , PhSCH 2 ; R 1 =H, Me; R 2 =Me, c-C 6 H 11 ) undergo highly dioastereoselective, Lewis acid catalyzed reactions with aliphatic and aromatic acetals R 3 CH(OR 4 ) 2 (R 3 =H, Me, t-Bu, Ph; R 4 =Me, CH 2 Ph) to afford cis-2-[RR 1 CH(R
RR 1 CH=CHOCHR 2 CO 2 SiMe 3 (R=Me, PhCH 2 , n-Bu, MeO 2 CCMe 2 CH) 类型的旋光单和二取代三甲基甲硅烷基 2-[(E)-1-烯氧基]乙酸酯2 , PhSCH 2 ; R 1 =H, Me; R 2 =Me, cC 6 H 11 ) 与脂肪族和芳香族缩醛 R 3 CH(OR 4 ) 2 (R 3 =H, Me) 发生高度对映选择性的路易斯酸催化反应, t-Bu, Ph; R 4 =Me, CH 2 Ph) 得到 cis-2-[RR 1 CH(R 3 CHOR 4 )]-5-R 2 -1,3-二氧戊环酮,对应于赤型非对映选择性醛醇涉及缩醛衍生的亲电子试剂和三甲基甲硅烷基酯氧跨烯醇醚双键的净顺面加成反应