N-Alkylation of N-arylsulfonyl-α-amino acid methyl esters by trialkyloxonium tetrafluoroborates
作者:Rosaria De Marco、Maria Luisa Di Gioia、Angelo Liguori、Francesca Perri、Carlo Siciliano、Mariagiovanna Spinella
DOI:10.1016/j.tet.2011.10.042
日期:2011.12
tetrafluoroborate is the reagent of choice for the direct and quantitative N-methylation. Further we extend our evaluation to the use of triethyloxonium tetrafluoroborate. This reagent shows to be very efficient in order to prepare N-ethyl derivatives of N-arylsulfonyl-α-amino acid methyl esters. An experimental protocol similar to that used for N-methylation with trimethyloxonium tetrafluoroborate is applied
N-(4-Nitrophenylsulfonyl)- and N-(Fluorenylmethoxycarbonyl)-N-ethyl Amino Acid Methyl Esters - A Practical Approach
作者:Emilia Lucia Belsito、Rosaria De Marco、Maria Luisa Di Gioia、Angelo Liguori、Francesca Perri、Maria Caterina Viscomi
DOI:10.1002/ejoc.201000256
日期:2010.8
An efficient one-pot preparation of N-ethyl-N-4-nitrophenylsulfonyl (nosyl) aminoacid methyl esters was accomplished by a simple N-ethylation reaction by using triethyloxonium tetrafluoroborate in the presence of N,N-diisopropylethylamine. The N-ethylated aminoacid methyl esters are obtained with total retention of stereochemistry at the original chiral centers. To further broaden the scope of this