Highly Enantioselective Synthesis of Orthogonally Protected (2S)-2,3-Diaminopropanoates through Catalytic Phase-Transfer Aza-Henry Reaction
作者:Gullapalli Kumaraswamy、Arigala Pitchaiah
DOI:10.1002/hlca.201100013
日期:2011.8
enantiomer‐enriched orthogonallyprotected different (2S)‐2,3‐diaminopropanoates and unnatural furyl‐substituted (tert‐butoxy)carbonyl (Boc) as well as (benzyloxy)carbonyl (Cbz) protected amino acid esters are accomplished by means of an enantioselective aza‐Henry reaction. A key feature of this protocol is organocatalysis as a genesis of chirality to ensure high enantioselectivity.
Enantioselective aza-Henry reaction using cinchona organocatalysts
作者:Luca Bernardi、Francesco Fini、Raquel P. Herrera、Alfredo Ricci、Valentina Sgarzani
DOI:10.1016/j.tet.2005.09.076
日期:2006.1
The aza-Henryreaction of imines with nitromethane was promoted by cinchona alkaloids and modified cinchona bases to give optically active β-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
Chiral ureas and thioureas supported on polystyrene for enantioselective aza-Henry reactions under solvent-free conditions
作者:Rafael Pedrosa、José M. Andrés、Deisy P. Ávila、Miriam Ceballos、Rodrigo Pindado
DOI:10.1039/c4gc02474e
日期:——
Chiral recoverable supported bifunctional ureas or thioureas promote highly enantioselective aza-Henry reactions under solvent-free conditions.
手性可回收支持的双功能脲或硫脲在无溶剂条件下促进高对映选择性的无溶剂条件下的氮杂-Henry反应。
Novel bifunctional thiourea–ammonium salt catalysts derived from amino acids: application to highly enantio- and diastereoselective aza-Henry reaction
作者:Hong-Yu Wang、Zhuo Chai、Gang Zhao
DOI:10.1016/j.tet.2013.04.079
日期:2013.6
development of new efficient and easily accessible catalysts has been one of the focuses in asymmetric phase-transfer catalysis. In this paper, a novel class of chiral bifunctional thiourea–ammonium phase-transfercatalysts were synthesized from commercially available α-amino acids. The structural modularity of these catalysts permits facile tunings to achieve optimum results, which was demonstrated
Bottom-Up Synthesis of Supported Thioureas and Their Use in Enantioselective Solvent-Free Aza-Henry and Michael Additions
作者:José M. Andrés、Noelia de La Cruz、María Valle、Rafael Pedrosa
DOI:10.1002/cplu.201500476
日期:2016.1
Two sets of supported chiral thioureas, which differ in the length of the tether that connects the chiral appendage to the polymer structure and the effective functionalization, have been prepared by copolymerization of styrene, novel styryl thioureas derived from l-valine, and divinylbenzene. The efficiency of these polymeric thioureas has been tested in two different enantioselective transformations