The osmium trichloride-catalyzed oxidation with peracetic acid of olefinic compounds bearing a protected α-amino acidgroup leads to α-ketol aminoacid precursors related to the 5-Hydroxy-4-Oxo-Norvaline antibiotic.
A diastereoselective tandem RCM approach to spiropiperidines
作者:Robert A.J. Wybrow、Andrew S. Edwards、Neil G. Stevenson、Harry Adams、Craig Johnstone、Joseph P.A. Harrity
DOI:10.1016/j.tet.2004.07.025
日期:2004.9
This paper outlines the stereocontrolled synthesis of a functionalised spiropiperidine through a diastereoselective tandem RCM reaction. The diastereoselectivity of this process was found to be strongly dependant on the nature of the catalyst; the less active first generation Ru-carbene complexes provided the desired spirocycle in high yield and with good stereocontrol. Additionally, the further functionalisation of the spiropiperidine was carried out through a regio- and stereoselective dihydroxylation reaction employing Donohoe's OsO4-TMEDA conditions. (C) 2004 Elsevier Ltd. All rights reserved.
N-Alkylation of diethyl acetamidomalonate: synthesis of constrained amino acid derivatives by ring-closing metathesis
作者:Sambasivarao Kotha、Kuldeep Singh
DOI:10.1016/j.tetlet.2004.11.013
日期:2004.12
An efficient method for N-alkylation of diethyl acetamidomalonate (DEAM) is reported. C-Alkenylation was achieved by treating the N-alkenylated DEAM with various electrophiles in the presence Of Cs2CO3. RCM reactions of C- and N-alkenylated products gave cyclic amino acid derivatives in good yields. (C) 2004 Published by Elsevier Ltd.