SmI2-Mediated Cross-Coupling of Nitrones with β-Silyl Acrylates: Synthesis of (+)-Australine
摘要:
The SmI2-mediated cross-coupling of nitrones with beta-silyl-alpha,beta-unsaturated esters, followed by zinc reduction, allows an efficient and highly diastereoselective preparation of beta-silyl lactams, which are precursors of beta-hydroxy lactams through Tamao-Fleming oxidation. By applying the method to a cyclic, carbohydrate-derived nitrone, a new synthesis of (+)-australine has been realized in only 11 steps and in 21% overall yield from L-xylose.
选择性糖基化:通过完全立体选择性硝酮环加成,Tamao-Fleming氧化和选择性α-葡萄糖基化为关键步骤,实现了天然木麻黄的全合成(1)和木麻黄的6 - O -α-葡萄糖苷的首次全合成(2)。两种化合物的生物学分析证明它们分别对葡糖淀粉酶NtMGAM和海藻糖酶Tre37A具有强大的选择性抑制特性,这使它们成为这些酶的最强抑制剂。
Activation of Si-Si Bonds for Copper(I)-Catalyzed Conjugate Silylation
作者:Laura Iannazzo、Gary A. Molander
DOI:10.1002/ejoc.201200767
日期:2012.9
silylation of α,β-unsaturated compounds. Optimal reaction conditions were first investigated to realize the conjugate addition of a nucleophilic silicon species to poorly electrophilic acceptors such as phenylvinyl sulfone by cleavage of the Si-Si bond of a disilane reagent. The scope of this reaction was extended to various electrophiles bearing different electron-withdrawing groups and afforded the