Leucine methyl and ethyl esters reacted with 3-bromobenzaldehyde and 4-chlorobenzaldehyde in anhydrous methanol in the presence of magnesium sulfate to afford the coresponding Schiff bases of the general formula (CH3)(2)CHCH2CH(COOR1)N=CHR2 [R-1 = CH3, C2H5, R-2 = 3-BrC6H4, 4-ClC6H4]. Their reduction with sodium tetrahydridoborate yielded N-benzyl derivatives (CH3)(2)CHCH2CH(COOR1)NHCH2R2, which were converted into N-acyl-N-benzyl derivatives (CH3)(2)CHCH2CH(COOR1)N(COR3)CH2R2 [R-3 = CH3, C6H5].
Leucine methyl and ethyl esters reacted with 3-bromobenzaldehyde and 4-chlorobenzaldehyde in anhydrous methanol in the presence of magnesium sulfate to afford the coresponding Schiff bases of the general formula (CH3)(2)CHCH2CH(COOR1)N=CHR2 [R-1 = CH3, C2H5, R-2 = 3-BrC6H4, 4-ClC6H4]. Their reduction with sodium tetrahydridoborate yielded N-benzyl derivatives (CH3)(2)CHCH2CH(COOR1)NHCH2R2, which were converted into N-acyl-N-benzyl derivatives (CH3)(2)CHCH2CH(COOR1)N(COR3)CH2R2 [R-3 = CH3, C6H5].
Direct Catalytic
<i>N</i>
‐Alkylation of α‐Amino Acid Esters and Amides Using Alcohols with High Retention of Stereochemistry
作者:Tao Yan、Ben L. Feringa、Katalin Barta
DOI:10.1002/cssc.202100373
日期:2021.6.8
naturally abundant chiral scaffolds such as α-amino acid esters or amides with widely abundant alcohols, without any racemization, is a demanding transformation that is of central importance for the synthesis of bio-active compounds. Herein a robust and general method was developed for the direct N-alkylation of α-amino acid esters and amides with alcohols. This powerful ruthenium-catalyzed methodology