A C2-Chiral Bis(amidinium) Catalyst for a Diels−Alder Reaction Constituting the Key Step of the Quinkert−Dane Estrone Synthesis
作者:Svetlana B. Tsogoeva、Gerd Dürner、Michael Bolte、Michael W. Göbel
DOI:10.1002/ejoc.200200635
日期:2003.5
A novel C2-chiralbis(amidinium) salt 12 has been synthesised from 5-(tert-butyl)isophthalic acid. The hydrogen-bond-mediated association of dienophiles 3a and 3b with the chiral host molecule 12 accelerates the Diels−Alderreactions with diene 2 by more than three orders of magnitude. In addition, enantioselective formation of the desired adducts is observed under catalysis with 12. Good ratios of