caa a22 4500 378866435 CHVBK 20180305123358.0 cr unu---uuuuu 161128e20030101xx s 000 0 eng 10.1351/pac200375020279 doi (NATIONALLICENCE)gruyter-10.1351/pac200375020279 Stereocontrolled construction of conformationally constrained and rigid bis(a-amino acid) derivatives [Elektronische Daten] [K. Undheim, Jon Efskind, G. B. Hoven] Cystine is regarded as a four-atom bridged bis(α-amino acid). The bridge between the two glycine moieties in cystine has been replaced with all-carbon C4-bridges between the α-carbon of the glycines. The products are dicarba analogs of cystine. Conformational constraints have been conferred on these molecules by insertion of cis- and trans- double bonds in the bridge, by alkylidene substituents, by insertion of a triple bond, by insertion of aromatic or heteroaromatic rings, or otherwise by ring formation. Particularly rigidified dicarba analogs of cystine have been prepared where the α-amino acid carbon is quaternary and part of tricyclic ring structures. Ru(II)-catalyzed ring-closing metathesis (RCM) reactions have been widely used in the preparation of cyclic amino acids. Conformational constraints in acyclic structures result from substitution by simple alkyl, alkenyl, or alkynyl groups at the α-amino acid carbon in the formation of α-quaternary amino acid derivatives. © 2013 Walter de Gruyter GmbH, Berlin/Boston Undheim K. Department of Chemistry, University of Oslo, N-0315 Oslo, Norway aut Efskind Jon Department of Chemistry, University of Oslo, N-0315 Oslo, Norway aut Hoven G. B. Department of Chemistry, University of Oslo, N-0315 Oslo, Norway aut Pure and Applied Chemistry De Gruyter 75/2-3(2003-01-01), 279-292 0033-4545 75:2-3<279 2003 75 pac https://doi.org/10.1351/pac200375020279 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1351/pac200375020279 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Undheim K. Department of Chemistry, University of Oslo, N-0315 Oslo, Norway aut NATIONALLICENCE 700 1- Efskind Jon Department of Chemistry, University of Oslo, N-0315 Oslo, Norway aut NATIONALLICENCE 700 1- Hoven G. B. Department of Chemistry, University of Oslo, N-0315 Oslo, Norway aut NATIONALLICENCE 773 0- Pure and Applied Chemistry De Gruyter 75/2-3(2003-01-01), 279-292 0033-4545 75:2-3<279 2003 75 pac CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter