Enantiospecific and diastereoselective synthesis of syn-β-amino-α-hydroxy acids
摘要:
The reaction of chiral alpha-hydroxy beta,gamma-unsaturated esters with tosyl isocyanate followed by cyclization of the resulting allylic carbamates with iodine in the presence of sodium carbonate provided trans-4,5-disubstituted 2-oxazolidinone derivatives in a highly diastereoselective manner. The subsequent removal of the iodo group and the protective functionality afforded the syn-beta-amino-alpha-hydroxy acids. Using the reaction sequence, (2R,3S)- and (2S,3R)-3-amino-2-hydroxy acids were synthesized with high enantioselectivity. (C) 1997 Elsevier Science Ltd. All rights reserved.
Copper-Catalyzed Enantioselective Henry Reaction of β,γ-Unsaturated α-Ketoesters with Nitromethane in Water
作者:Yanan Li、Yekai Huang、Yang Gui、Jianan Sun、Jindong Li、Zhenggen Zha、Zhiyong Wang
DOI:10.1021/acs.orglett.7b03299
日期:2017.12.1
A highly enantioselective Henry reaction of β,γ-unsaturated α-ketoesters with nitromethane in water by virtue of chiral copper complexes has been developed. A series of unsaturated β-nitro-α-hydroxy esters bearing tetrasubstituted carbon stereocenters were obtained exclusively with high yields and excellent enantioselectivities. This method could avoid tedious anaerobic anhydrous manipulation and reduce
Enantioselective Conjugate Addition of <i>N</i>,<i>N</i>-Dialkylhydrazones to α-Hydroxy Enones
作者:David Monge、Eloísa Martín-Zamora、Juan Vázquez、Manuel Alcarazo、Eleuterio Álvarez、Rosario Fernández、José M. Lassaletta
DOI:10.1021/ol071055+
日期:2007.7.1
The activation of alpha-hydroxy enones by the Zn(OTf)2/tBuBOX catalyst enables the enantioselectiveconjugateaddition of 1-methyleneaminopyrrolidine as a neutral d1 synthon. Experimental evidence supports a stereochemical model where a triflate ligand controls the geometry of the catalyst-substrate complex by means of a OH-OTf hydrogen bond. The synthesis of beta-cyano acids illustrates the potential
Organocatalytic Conjugate Addition of Formaldehyde <i>N,N</i>-Dialkylhydrazones to β<i>,</i>γ-Unsaturated α-Keto Esters
作者:Raquel P. Herrera、David Monge、Eloísa Martín-Zamora、Rosario Fernández、José M. Lassaletta
DOI:10.1021/ol071292c
日期:2007.8.1
(1S,2R)-1-Aminoindan-2-ol-derived thioureas behave as efficient H-bonding organocatalysts for the nucleophilic conjugate addition of formaldehyde hydrazones to beta,gamma-unsaturated alpha-keto esters as enoate surrogates, affording the corresponding adducts in good yields and enantioselectivities.
Chiral N-heterocyclic carbene (NHC) catalyzed redox reactions of racemic alpha-chloroaldehydes lead to the generation of chiral enolates suitable for highly enantioselective inverse-electron-demand 1-oxodiene Diels-Alder reactions. Significantly, these reactions proceed under mild, operationally friendly reaction conditions (EtOAc, room temperature, 2-8 h) using less than 1 mol % of a chiral N-mesityl
ENANTIOSELECTIVE REACTIONS CATALYZED BY CHIRAL TRIAZOLIUM SALTS
申请人:Bode Jeffrey
公开号:US20100210452A1
公开(公告)日:2010-08-19
This invention provides a convenient method for converting imines and other electrophiles into heterocyclic ring systems. The process does not require the use of metallic reagents, and is catalyzed by an organic heterocyclic carbene catalyst. Accordingly, it produces the desired compounds without the concomitant production of a large volume of metallic waste. Chiral heterocyclic carbene catalysts of the invention and methods of using these catalysts produce chiral heterocycles in high enantiomeric and diastereomeric excess.