Synthesis of N-(Triisopropylsilyl)- and N-(tert-Butyldimethylsilyl)aldimines and Their Application in the Synthesis of β-Lactams
作者:Gianfranco Cainelli、Daria Giacomini、Paola Galletti
DOI:10.1055/s-1997-1276
日期:1997.8
A new and efficient synthesis of N-(TIPS)imines and N-(TBDMS)-imines starting from enolizable and non-enolizable aldehydes is described. We tested the reactivity of these imines in the preparation of β-lactams. N-(TBDMS)imines effectively give N(-TBDMS)azetidinones with a trans stereochemistry of the ring substituents, complementing N-(TMS)imines which instead afford cis β-lactams. In contrast, N-(TIPS)imines react with ester enolates in few cases because of the extremely low rate of the ring-closure step, so that a decomposition of enolates occurred.
描述了一种新的高效合成N-(TIPS)亚胺和N-(TBDMS)-亚胺的方法,该方法以可酮化和不可酮化的醛为起始材料。我们测试了这些亚胺在β-内酯制备中的反应性。N-(TBDMS)亚胺有效地生成N(-TBDMS)氮杂环丁酮,且环取代基的立体化学为trans,这与N-(TMS)亚胺相辅相成,后者生成的是cis β-内酯。相比之下,由于环闭合步骤的反应速率极低,N-(TIPS)亚胺与酯烯醇盐的反应在少数情况下发生,导致烯醇盐的分解。