Enantioselective Aza-Henry Reaction Using Cinchona Organocatalysts
Luca Bernardi, Francesco Fini, Raquel P. Herrera, Alfredo Ricci, Valentina Sgarzani. Enantioselective Aza-Henry Reaction Using Cinchona Organocatalysts. Tetrahedron . 2006, Vol. 62 / 2006, p. 375-2006.
<p>The aza-Henry reaction of imines with nitromethane was promoted by cinchona alkaloids and modified cinchona bases to give optically active b-nitroamines. Various N-protected imines were examined as substrates. N-Boc, N-Cbz, and N-Fmoc protected imines gave the best results in terms of chemical yields and enantioselectivities. After a careful screening of a series of chiral bases, very good enantioselectivities up to 94% ee were obtained using a cinchona-based thiourea organocatalyst under the optimized reaction conditions.</p>
<p>The aza-Henry reaction of imines with nitromethane was promoted by cinchona alkaloids and modified cinchona bases to give optically active b-nitroamines. Various N-protected imines were examined as substrates. N-Boc, N-Cbz, and N-Fmoc protected imines gave the best results in terms of chemical yields and enantioselectivities. After a careful screening of a series of chiral bases, very good enantioselectivities up to 94% ee were obtained using a cinchona-based thiourea organocatalyst under the optimized reaction conditions.</p>