The activation potentials of the p-toluenesulfonyl and benzoyl groups as determined by cyclic voltammetry when they are linked to indole or imidazole are less negative than when these groups are linked to aliphatic amines. This makes them most suitable for side-chainprotection of tryptophan and histidine, as it allows mild selective cleavage not only by controlled-potential electrolysis but also by
The total synthesis of three (+)-Pilocarpine analogs (9a,9b and 9c) starting from L-Histidine, is described. The structure of the three new analogs contains the 2-oxazolidone structure.
Histidine and deuterium labelled histidine by asymmetric catalytic reduction with gaseous H2 or D2; the role of strong non-coordinating acids
作者:E. Cesarotti、I. Rimoldi、D. Zerla、G. Aldini
DOI:10.1016/j.tetasy.2007.12.013
日期:2008.2
An efficient and convenient route for the preparation of natural and unnatural histidine by asymmetric hydrogenation with rhodium-phosphine complexes is described. The reductions were performed in the presence of HBF(4) to generate an essential imidazolyl cation. Stereoselective incorporation of D(2) in the alpha,beta-positions was obtained by catalytic deuteration in the presence of MeOD. (c) 2008 Elsevier Ltd. All rights reserved.