Syntheses of isotopically labelled L-α-amino acids with an asymmetric centre at C-3
作者:John R. Harding、Rachael A. Hughes、Nicholas M. Kelly、Andrew Sutherland、Christine L. Wilis
DOI:10.1039/b005172l
日期:——
Approaches are described to the synthesis of a series of isotopicallylabelled L-α-amino acids each with an asymmetric centre at C-3, including isoleucine, allo-isoleucine, threonine and allo-threonine. The methods may be simply adapted for the selective incorporation of an isotopiclabel at each site of L-valine including the selective labelling of either diastereotopic methyl group with carbon-13
Chemo-enzymatic synthesis of isotopically labelled L-Valine, L-Isoleucine and allo-isoleucine
作者:Nicholas M. Kelly、R. Gordon Reid、Christine L. Wellis、Peter L. Winton
DOI:10.1016/0040-4039(96)00053-6
日期:1996.2
catalysed reactions (Candida cylindracea lipase to hydroluse the ester and leucine dehydrogenase to catalyse the reductive amination of the ketone). This strategy may be simply adapted for the selective labelling of each site of the L-amino acid.
Asymmetric alkylation reactions of chiral imide enolates. A practical approach to the enantioselective synthesis of .alpha.-substituted carboxylic acid derivatives
作者:D. A. Evans、M. D. Ennis、D. J. Mathre
DOI:10.1021/ja00370a050
日期:1982.3
Toward Ideality: The Synthesis of (+)-Kalkitoxin and (+)-Hydroxyphthioceranic Acid by Assembly-Line Synthesis
作者:Sebastien Balieu、Gayle E. Hallett、Matthew Burns、Teerawut Bootwicha、John Studley、Varinder K. Aggarwal
DOI:10.1021/ja512875g
日期:2015.4.8
The iterative homologation of boronic esters using chiral lithiated benzoate esters and chloromethyllithium has been applied to the highly efficient syntheses of two natural products, (+)-kalkitoxin and (+)-hydroxyphthioceranic acid. The chiral lithiated benzoate esters (>99% ee) were generated from the corresponding stannanes, which themselves were prepared by HoppeBeak deprotonation of ethyl 2,4,6-triisopropyl-benzoate with s-BuLi in the presence of (+)- or (-)-sparteine and trapping with Me3SnCl followed by recrystallization. In addition, it was found that purification between several homologations could be avoided, substantially increasing both chemical and manpower efficiency. In the case of (+)-kalkitoxin, six iterative homologations were conducted on commercially available p-MeOC(6)H(4)CH(2)Bpin to build up the core of the molecule before the C-B bond was converted into the desired CN bond, without purification of intermediates. In the case of (+)-hydroxyphthioceranic acid, 16 iterative homologations were conducted on p-MeOC(6)H(4)Bpin with only four intermediate purifications before oxidation of the C-B bond to the desired alcohol. The stereocontrolled and efficient syntheses of these complex molecules highlight the power of iterative chemical synthesis using boronic esters.