Tandem Asymmetric Conjugate Addition/α-Alkylation Using (<i>S</i>,<i>S</i>)-(+)-Pseudoephedrine as Chiral Auxiliary
作者:Efraim Reyes、Jose L. Vicario、Luisa Carrillo、Dolores Badía、Ainara Iza、Uxue Uria
DOI:10.1021/ol060720w
日期:2006.6.1
beta-unsaturated amides derivedfrom the chiralamino alcohol (S,S)-(+)-pseudoephedrine undergo a very clean and diastereoselective tandem conjugate addition/alpha-alkylation reaction. Excellent results have been achieved using a wide range of differently substituted conjugate acceptors, organolithium reagents, and alkyl halides. The chiralauxiliary could be easily removed from the obtained adducts by
(<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine as Chiral Auxiliary in Asymmetric Conjugate Addition and Tandem Conjugate Addition/α-Alkylation Reactions
作者:Efraim Reyes、Jose L. Vicario、Luisa Carrillo、Dolores Badía、Uxue Uria、Ainara Iza
DOI:10.1021/jo061205e
日期:2006.9.1
Organolithium reagents undergo highly regio- and diastereoselective 1,4-addition to (S,S)-(+)-pseudoephedrine enamides furnishing the corresponding β-alkyl-substituted adducts in excellent yields and diastereoselectivities. In addition, the intermediate lithium enolates generated after the conjugate addition step undergo a highly diastereoselective alkylation reaction, furnishing α,β-dialkyl-substituted