(<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine as Chiral Auxiliary in Asymmetric Aza-Michael Reactions. Unexpected Selectivity Change when Manipulating the Structure of the Auxiliary
作者:Juan Etxebarria、Jose L. Vicario、Dolores Badia、Luisa Carrillo、Nerea Ruiz
DOI:10.1021/jo051207j
日期:2005.10.1
the structure of the chiralauxiliary, which has allowed a diastereodivergent procedure to be set up for performing asymmetric aza-Michael reactions using the same chirality source. Finally, the adducts obtained in the asymmetric aza-Michael reaction have proven to be very versatile synthetic intermediates in the preparation of other interesting compounds such as β-amino esters, γ-amino alcohols, and
Asymmetric Synthesis of β-Amino Esters by Aza-Michael Reaction of α,β-Unsaturated Amides Using (<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine as Chiral Auxiliary
作者:Juan Etxebarria、Jose L. Vicario、Dolores Badia、Luisa Carrillo
DOI:10.1021/jo0357768
日期:2004.4.1
Chiral nonracemic β-amino esters were prepared in good yields and enantioselectivities using the diastereoselective conjugate addition of nitrogen nucleophiles to α,β-unsaturated amides derived from (S,S)-(+)-pseudoephedrine as the key step. In this way, several β-amino amide adducts were prepared using different conjugate acceptors and two different lithium benzylamides as nucleophiles. These adducts