1353643-09-0Relevant articles and documents
Synthesis of new N-ethyl dehydroamino acid derivatives: N-ethyl β,β-dibromo, N-ethyl β-bromo β-substituted, and N-ethyl β,β-disubstituted N-protected dehydroamino acid methyl esters
Monteiro, Luis S.,Andrade, Juliana J.,Suarez, Ana C.
, p. 6764 - 6772 (2011/12/21)
Recently, we reported the use of a sequence of alkylation and dehydration methodologies to obtain new non-proteinogenic amino acids (N-ethyl α,β-dehydroamino acids) from the methyl esters of N-(4-nitrophenylsulfonyl) β-hydroxy amino acids. Thus, it was possible to obtain for the first time, non-natural amino acids that incorporate both N-ethyl and α,β-dehydro moieties. Herein, we report the application of this N-alkylation procedure to several methyl esters of β,β-dibromo and β-bromo β-substituted dehydroamino acids protected with standard amine protecting groups such as tert-butyloxycarbonyl, benzyloxycarbonyl, and (4-nitrobenzyl)oxycarbonyl, as well as acyl and sulfonyl groups. The procedure allows the synthesis of the methyl esters of N-protected N-ethyl β,β-dibromo and N-ethyl β-bromo β-substituted dehydroamino acids in fair to high yields. Some of these N-ethylated dehydroamino acid derivatives were used as substrates in cross-coupling reactions to give β,β-disubstituted N-ethyldehydroalanine derivatives. N-Ethylation of the methyl esters of β,β-dibromo and β-bromo, β-substituted dehydroamino acids protected with standard amine protecting groups is reported. The procedure allows the corresponding N-ethyl derivatives to be obtained in fair to high yields. These substrates can be applied in cross-coupling reactions, and constitute valuable synthons for the synthesis of N-ethyl derivatives. Copyright
