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Titolo:
CONVENIENT ROUTE TO GAMMA-NITRO-ALPHA-AMINO ACIDS - CONJUGATE ADDITION OF NITROALKANES TO DEHYDROALANINE DERIVATIVES
Autore:
CROSSLEY MJ; FUNG YM; POTTER JJ; STAMFORD AW;
Indirizzi:
UNIV SYDNEY,SCH CHEM SYDNEY NSW 2006 AUSTRALIA
Titolo Testata:
Journal of the Chemical Society. Perkin transactions. I
fascicolo: 6, , anno: 1998,
pagine: 1113 - 1121
SICI:
0300-922X(1998):6<1113:CRTGA->2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
BETA-HYDROXYAMINO ACIDS; PEPTIDES; ESTERS; ELIMINATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
M.J. Crossley et al., "CONVENIENT ROUTE TO GAMMA-NITRO-ALPHA-AMINO ACIDS - CONJUGATE ADDITION OF NITROALKANES TO DEHYDROALANINE DERIVATIVES", Journal of the Chemical Society. Perkin transactions. I, (6), 1998, pp. 1113-1121

Abstract

gamma-Nitro-alpha-amino acid derivatives are obtained in good yield from the base-catalysed conjugate addition of nitroalkanes to N-protected dehydroalanine eaters (methyl 2-amidoacrylates). The outcome of thereaction is dependent on the N-protecting group (the ease of the product formation correlates with the electron-withdrawing ability and hence stabilising effect on the adduct alpha-anion of the 2-substituent in the order phthalimido > benzyloxycarbonylamino > acetamido), the nitroalkane, and on the reaction conditions. Conditions were established in reactions of methyl 2-phthalimidoacrylate 4 with nitromethane for selectively obtaining 1:1-, 2:1- or 3:1-adducts. Good yields of the 1:1-adducts are obtained when the reaction is carried out with an excess of nitroalkane. Restricting the amount of nitromethane gives rise to the higher adducts. Similarly, reactions of 4 with nitroethane can be adjusted to give 1:I-or 2: l-adducts selectively. These reactions occurwith little or no diastereoselectivity. As a model for a dehydroalanine residue in a peptide chain, the diamide N-cyclohexyl-2-acetamidoacrylamide 7 has been prepared. This dehydroalanine reacts with 2-nitropropane and with nitromethane in refluxing tert-butyl alcohol to give reasonable yields of 1:1-adducts. As the nitro group of the resultant gamma-nitro-alpha-amino acid derivatives can be transformed into a variety of other functionalities, the methodology described in this paper offers a versatile entry to a range of gamma-substituted alpha-amino acids.

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Documento generato il 18/09/20 alle ore 18:36:32