title: Two separate and distinct syntheses of stereospecifically deuteriated samples of (2S)-proline.
abstract: Two distinct syntheses of samples of the amino acid L-proline which are stereospecifically deuteriated on the beta-carbon atom are reported. In the first of these, the labelled diazoketones 6, prepared by a chemico-enzymatic synthesis, have been photolysed in alkaline conditions to give the corresponding labelled methyl pyroglutamates 10 via hydrolysis and intramolecular trapping of the resultant ketene intermediates 9. These were then converted into (2S,3S)-[3-(2)H1]- and (2S,3R)-[2,3-(2)H2]-proline, 1a and 1b respectively. The second synthesis provides (2S)-[3,3-(2)H2]-, (2S,3S)- and (2S,3R)-[3-(2)H1]-proline, 1d, 1a and 1c respectively, and has as its key step the highly stereoselective hydrolysis of the silylenol ethers 14 and 14a respectively in which deuteriation or protonation occurs from the re-face of the enol ether.
authors.affiliation: Department of Chemistry, University of Sussex, Falmer, Brighton, UK BN1 9QJ.
authors.forename: Paul
authors.initials: P
authors.lastname: Barraclough
authors.forename: Petra
authors.initials: P
authors.lastname: Dieterich
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Spray
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Young
mesh_terms: D003903:Deuterium / Q000737:chemistry*; D015394:Molecular Structure; D011392:Proline / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D011392:Proline; D003903:Deuterium