Diastereoselective synthesis of cyclopropane amino acids using diazo compounds generated in situ.
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].
Adams
Luke A
LA
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
Aggarwal
Varinder K
VK
Bonnert
Roger V
RV
Bressel
Bettina
B
Cox
Russell J
RJ
Shepherd
Jon
J
de Vicente
Javier
J
Walter
Magnus
M
Whittingham
William G
WG
Winn
Caroline L
CL
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
D000596:Amino Acids; D003521:Cyclopropanes; D003979:Diazonium Compounds