3-Aza-8,10-dioxa-bicyclo[5.2.1]decane (9-exo BTKa) carboxylic acid as a new reverse turn inducer: synthesis and conformational analysis of a model peptide
摘要:
Dipeptide isostere 5, belonging to the class of 9-exo BTKa, was synthesised starting from R,R-tartaric acid and 4-nitro-1-(3-nitrophenyl)butan-1-one. The nine-membered lactam showed interesting structural features and was inserted in a 5-residue model peptide. The conformational properties of this modified peptide have been Studied by NMR and molecular modelling, indicating that Compound 5 acted as it reverse turn inducer. (c) 2005 Elsevier Ltd. All rights reserved.
Selectivity of Daucus carota roots and baker’s yeast in the enantioselective reduction of γ-nitroketones
摘要:
The enantioselective reduction of a series of aromatic gamma-nitroketones was achieved by using Daticus carota roots in water, which afforded the corresponding (S)-alcohols with ees ranging from 73% to 100%. A comparison of these results with the data obtained by reducing the same substrates with baker's yeast resulted in D. carota always being more enantioselective than baker's yeast, although a lower number of substrates were reduced. The possible influence of the aromatic ring substituents on the reaction outcome is also discussed. (c) 2005 Elsevier Ltd. All rights reserved.