title: Diastereoselective synthesis of cyclopropane amino acids using diazo compounds generated in situ.
abstract: A simple and high-yielding method for the preparation of cyclopropane amino acids is described. The novel method involves the one-pot cyclopropanation of readily available dehydroamino acids using aryl and unsaturated diazo compounds generated in situ from the corresponding tosylhydrazone salts. It was found that thermal 1,3-dipolar cycloaddition followed by nitrogen extrusion gave the cyclopropane amino acid derivatives with good E selectivity, while reactions in the presence of meso-tetraphenylporphyrin iron chloride gave predominantly the corresponding Z isomers. The synthetic utility of this process was demonstrated in the synthesis of (+/-)-(Z)-2,3-methanophenylalanine [(+/-)-(Z)-1], the anti-Parkinson (+/-)-(E)-2,3-methano-m-tyrosine [(+/-)-(E)-2], and the natural product (+/-)-coronamic acid [(+/-)-3].
authors: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
authors: Luke A
authors: LA
authors: Adams
authors: Varinder K
authors: VK
authors: Aggarwal
authors: Roger V
authors: RV
authors: Bonnert
authors: Bettina
authors: B
authors: Bressel
authors: Russell J
authors: RJ
authors: Cox
authors: Jon
authors: J
authors: Shepherd
authors: Javier
authors: J
authors: de Vicente
authors: Magnus
authors: M
authors: Walter
authors: William G
authors: WG
authors: Whittingham
authors: Caroline L
authors: CL
authors: Winn
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D003979:Diazonium Compounds / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D003521:Cyclopropanes; D003979:Diazonium Compounds