Synthesis and Reactivity of β‐Bromo‐β‐Substituted Dehydroalanines

Abstract

The methyl ester of N-tert-butoxycarbonyl-(Z)-β-bromo-β-(1,2,4-triazol-1-yl)dehydroalanine was prepared by treatment of the methyl ester of N-tert-butoxycarbonyl-(E)-β-(1,2,4-triazol-1-yl)dehydroalanine with N-bromosuccinimide (NBS), followed by Et 3 N. The reactivities of this compound and of our previously synthesized methyl ester of N-tert-butoxycarbonyl-β,β-dibromodehydroalanine towards several nucleophiles were studied, and it was found that these compounds react with oxygen nucleophiles to give the corresponding α-alkoxy-β,β-disubstituted alanines. Addition to

Comparative effect ofN-substituted dehydroamino acids and α-tocopherol on rat liver lipid peroxidation activities

“…In dehydroalanine type compounds, free radicals are most probably attacked to the carbon-carbon double bond and the resulting radical adduct is formed easily by the effect of the groups next to the dehydro unit. N,Ndiprotected dehydroalanine derivatives were found excellent substrates of Michael addition reactions by Ferreira et al [25,26,36,37] but the mono-protected derivatives were found relatively poorer Michael acceptors than the other tested compounds [25,26]. There was no significant correlation found between the antioxidant activity results and the Michael acceptor properties of the compounds.…”

Synthesis and photophysical studies of new pyrenylamino acids

“…Compound Z-3 was obtained by a sequential Michael addition reaction between the methyl ester of the N-(4-toluenesulfonyl)-N-(tertbutoxycarbonyl)dehydroalanine and 1,2,4-triazole, followed by halogenation with NBS and NEt 3 . 12 Compound 4 was obtained after α-addition, β-substitution and β-elimination. The stereochemistry of compound 4 was determined by NOE difference experiments by irradiating the β-CH and observing a NOE enhancement on the =NCH 2 protons.…”

“…9,10 Continuing our work concerning the synthesis of non-proteinogenic fluorescent amino acids, we decided to prepare three new pyrenylamino acids using as substrates β,β-disubstituted dehydroalanine derivatives and a strategy previously developed by us. 11,12 Recently, we described the synthesis of α-substituted-β,βdibromoalanines from a β,β-dibromodehydroalanine by treatment with oxygen nucleophiles and primary amines.…”

“…Furthermore, by reacting a β-bromo-β-triazolyldehydroalanine with primary amines it was possible to prepare several αamino-β-iminoalanines. 12 These compounds afforded the αaminoglycines when treated with silica in dichloromethane. 12 In this work, this methodology was applied to the synthesis of a α-(pyren-1-yl)methylamino-β,β-dibromoalanine, a α-(pyren-1-yl)methylamino-β-iminoalanine and a α-(pyren-1yl)methylaminoglycine.…”

“…12 These compounds afforded the αaminoglycines when treated with silica in dichloromethane. 12 In this work, this methodology was applied to the synthesis of a α-(pyren-1-yl)methylamino-β,β-dibromoalanine, a α-(pyren-1-yl)methylamino-β-iminoalanine and a α-(pyren-1yl)methylaminoglycine. The photophysical properties of these compounds were studied in several solvents of different polarity and time-resolved fluorescence studies were performed.…”