TMS enol ethers in good yield. These enolates undergo spontaneous addition to aldehydes to provide the aldol adducts syn-4, 5a-e in high yield and selectivity (dr ). More electron rich aldehydes tend to be more diastereoselective. The reaction of these enolates with aldehydes is also catalyzed by the chiral phosphoramide (S,S)-1 to provide anti-4, 5a-e in good to excellent diastereo- (dr ) and enantioselectivity
通过
汞(II)催化的易位反应,由它们的TMS烯醇醚制备
环戊酮和
环庚酮的三
氯甲
硅烷基烯醇化物,收率很高。这些烯醇化物进行自发除醛以提供醛醇加合物顺- 4,5A-E在高产率和选择性(DR )。更多的富电子醛往往具有更高的非对映选择性。这些烯醇化物与醛的反应也由手性
磷酰胺(S,S)-1催化以提供抗- 4,在5A-E良好至优异的diastereo-(DR )和对映选择性(ER)。在这些情况下,只有在空间上相似的
苯甲醛衍
生物上,趋势才明显。此外,优化研究表明,在催化反应中可能存在两种机理不同的途径。