176796-27-3Relevant academic research and scientific papers
Diastereoselective Synthesis of Unnatural Amino Acids by Alkylation of α- Tert-Butanesulfinamide Auxiliary-Bound Enolates
Dwulet, Natalie C.,Zolfaghari, Tina A.,Brown, Molly L.,Cannon, Jeffrey S.
, p. 11510 - 11518 (2018)
A new chiral auxiliary for the diastereoselective alkylation of amino ester enolates that takes advantage of chiral information stored on the enolate side of the amino ester substrate has been developed. Chiral α-sulfinamido esters were alkylated under basic conditions in good yields (up to 90%) and good to high diastereoselectivities (generally >6:1) to provide unnatural mono- and α,α-disubstituted amino acid derivatives. This auxiliary allowed for the ready conversion of ester functionality without the need for esoteric reagents. Furthermore, the auxiliary is easily removed to provide enantiopure amino acids. Computational studies revealed that a chelated transition state governs electrophile addition from the convex face of a transient bicyclic intermediate. This method allows ready access to enantioenriched natural and unnatural amino acids.
Towards a universal organocatalyst for the synthesis of enantioenriched phenylalanine derivatives by enantioselective decarboxylative protonation
Pigeaux, Morgane,Laporte, Romain,Harrowven, David C.,Baudoux, Jér?me,Rouden, Jacques
, p. 4599 - 4603 (2016/09/23)
Access to enantioenriched non-proteogenic phenylalanine derivatives is described using the enantioselective decarboxylative protonation reaction of amidohemimalonate esters catalysed by various cinchona-based compounds. This study compares the catalytic efficiency as well as the enantioselectivity induced by three types of common organocatalysts, namely thioureas, squaramides and bis-cinchona squaramides. One of the main outcome of this work is the observation of a significant influence of the N-protecting group of the hemimalonate on its interaction with the catalyst. This methodology carried out under mild conditions exhibits good substrate scope and functional group tolerance. A substoichiometric amount of catalyst can also be used in certain cases while affording good yields and selectivities.
Double stereodifferentiation in the catalytic asymmetric aziridination of imines prepared from α-chiral amines
Huang, Li,Zhang, Yu,Staples, Richard J.,Huang, Rui H.,Wulff, William D.
, p. 5302 - 5313 (2012/05/20)
The catalytic asymmetric aziridination of imines and diazo compounds (AZ reaction) mediated by boroxinate catalysts derived from the VANOL and VAPOL ligands was investigated with chiral imines derived from five different chiral, disubstituted, methyl amines. The strongest matched and mismatched reactions with the two enantiomers of the catalyst were noted with disubstituted methyl amines that had one aromatic and one aliphatic substituent. The synthetic scope for the AZ reaction was examined in detail for α-methylbenzyl amine for cis-aziridines from α-diazo esters and for trans-aziridines from α-diazo acetamides. Optically pure aziridines could be routinely obtained in good yields and with high diastereoselectivity and the minor diastereomer (if any) could be easily separated. The matched case for cis-aziridines involved the (R)-amine with the (S)-ligand, but curiously, for trans-aziridines the matched case involved the (R)-amine with the (R)-ligand for imines derived from benzaldehyde and n-butanal, and the (R)-amine with the (S)-ligand for imines derived from the bulkier aliphatic aldehydes pivaldehyde and cyclohexane carboxaldehyde.
Microwave assisted mild, rapid, solvent-less, and catalyst-free chemoselective N-tert-butyloxycarbonylation of amines
Dighe, Satish N.,Jadhav, Hemant R.
, p. 5803 - 5806 (2012/10/29)
Microwave assisted simple, rapid, solventless, and catalyst-free chemoselective method for the protection of amino group in aromatic, aliphatic, heterocyclic, aralkyl amines, phenyl hydrazine, and amino acid esters in good to excellent isolated yield (83-98%) in short reaction time (2-12 min) has been reported.
Multicomponent catalytic asymmetric aziridination of aldehydes
Gupta, Anil K.,Mukherjee, Munmun,Wulff, William D.
, p. 5866 - 5869 (2011/12/15)
The first multicomponent catalytic asymmetric aziridination reaction is developed to give aziridine-2-carboxylic esters with very high diastereo- and enantioselectivity from aromatic and aliphatic aldehydes. This new method pushes the boundary of the aziridination reaction to substrates that failed with preformed imines.
A facile method for the preparation of MOM-protected carbamates
Barnes, David M.,Barkalow, Jufang,Plata, Daniel J.
supporting information; experimental part, p. 273 - 275 (2009/08/08)
(Chemical Equation Presented) A novel method for the preparation of MOM-protected carbamates is described that avoids the use of MOM-Cl, a regulated carcinogen. The two-step, one-pot procedure generates a reactive N-chloromethyl carbamate that is quenched
