Enantiospecific and diastereoselective synthesis of syn-β-amino-α-hydroxy acids
作者:Hideyuki Sugimura、Masayuki Miura、Nobuko Yamada
DOI:10.1016/s0957-4166(97)00595-8
日期:1997.12
The reaction of chiral alpha-hydroxy beta,gamma-unsaturated esters with tosyl isocyanate followed by cyclization of the resulting allylic carbamates with iodine in the presence of sodium carbonate provided trans-4,5-disubstituted 2-oxazolidinone derivatives in a highly diastereoselective manner. The subsequent removal of the iodo group and the protective functionality afforded the syn-beta-amino-alpha-hydroxy acids. Using the reaction sequence, (2R,3S)- and (2S,3R)-3-amino-2-hydroxy acids were synthesized with high enantioselectivity. (C) 1997 Elsevier Science Ltd. All rights reserved.
Zur Biosynthese der Rubratoxine
作者:Sirkku Nieminen、Trevor G. Payne、Peter Senn、Christoph Tamm
DOI:10.1002/hlca.19810640722
日期:1981.11.4
In order to check the hypothesis that rubratoxin B (2), a C26-metabolite, is formed biogenetically by head-to-tail coupling of two identical C13-precursors derived from decanoic acid and oxaloacetic acid, two labelled forms of the postulated C13-intermediate 2-((E)-1'-octenyl)-3-[14C]methyl- and 2-((E)-1'-octenyl)-3-[13C]-methylmaleic anhydride (10), were synthesized. The labelled compounds 10 as well