Regio- and Stereoselective Chan-Lam-Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines
Efficient and scalable Cu(II)-mediated enol esterification methodology of carboxylic acids from alkenyl boroxines and boronic acids is presented. The reaction shows a wide scope in aliphatic and aromatic carboxylic acids in combination with several alkenyl boroxines. In the case of 2-substituted alkenyl boroxines the double bond configuration was fully retained in the enol ester product. Also N-hydroxyimides and imides could be transformed in the respective amidooxy vinyl enol ethers and vinyl enamides. Finally, with the exception of methionine, all other 19 canonical amino acids showed their compatibility to give the enol esters in a stereoselective fashion. (Figure presented.).
Steemers, Luuk,Wijsman, Linda,van Maarseveen, Jan H.
supporting information
p. 4241 - 4245
(2018/10/02)
Method for preparing ester linked peptide-carbohydrate conjugates
A method of producing an ester linked carbohydrate-peptide conjugate is provided comprising: (a) providing a vinyl ester amino acid group, and (b) reacting the vinyl ester amino acid with a carbohydrate acyl acceptor in the presence of an enzyme, to produ
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(2008/06/13)
Ready protease-catalyzed synthesis of carbohydrate-amino acid conjugates.
The protease-catalyzed synthesis of amino acid est-carbohydrate conjugates as glycopeptide analogues has been achieved in a highly regioselective and carbohydrate-specific manner using amino acid vinyl ester acyl donors and minimally or completely unprotected carbohydrate acyl acceptors, which together probed active sites of proteases to reveal yield efficiencies that are modulated by the carbohydrate C-2 substitutent, and that may be exploited to allow selective one-pot syntheses.
Boyer,Stanchev,Fairbanks,Davis
p. 1908 - 1909
(2007/10/03)
Probing the specificity of the S1', leaving group, site of subtilisin Bacillus lentus using an enzyme-catalyzed transesterification reaction
Subtilisin Bacillus lentus catalyzes transesterifications between N- acetyl-L-phenylalanine vinyl ester and a wide range of alcohols. Reaction yields are high when primary alcohols are used, and quantitative with methanol. With chiral alcohols, the reaction is enantioselective, and the stereoselectivity is reversed on going from open chain secondary alcohols to β-branched primary alcohols. A model is proposed to account for this change in absolute configuration preference.
Lloyd, Richard C.,Dickman, Michael,Jones, J. Bryan
p. 551 - 561
(2007/10/03)
A new methodology for the preparation of vinyl esters
A new methodology has been developed for the preparation of unsubstituted enol esters. Its application is demonstrated by the obtainment of vinyl aromatic α-amino esters. A brief investigation of the preparation of other hydrophobic vinyl esters proved successful. Because of the mild reaction conditions employed, it is believed this route should provide access to other enol esters.
Weinhouse,Janda
p. 81 - 83
(2007/10/02)
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