title: The use of enantiomerically pure ketene dithioacetal bis(sulfoxides) in highly diastereoselective intramolecular nitrone cycloadditions. Application in the total synthesis of the beta-amino acid (-)-cispentacin and the first asymmetric synthesis of cis-(3R,4R)-4-amino-pyrrolidine-3-carboxylic acid.
abstract: Intramolecular 1,3-dipolar nitrone cycloaddition onto an enantiomerically pure ketene dithioacetal dioxide using a three-carbon tether gave the corresponding 5,5-disubstituted isoxazolidine as a single diastereomer in good yield. This reaction has been used as the key step in an asymmetric synthesis of the naturally occurring antibiotic, (-)-cispentacin. An asymmetric synthesis of 4-amino-pyrrolidine-3-carboxylic acid has also been carried out using the intramolecular nitrone cycloaddition as the stereocontrolling step.
authors.affiliation: Department of Chemistry, University of Bristol, Cantock's Close, Bristol, UK.
authors.forename: Varinder K
authors.initials: VK
authors.lastname: Aggarwal
authors.forename: Stephen
authors.initials: S
authors.lastname: Roseblade
authors.forename: Rikki
authors.initials: R
authors.lastname: Alexander
mesh_terms: D000935:Antifungal Agents / Q000138:chemical synthesis; D002264:Carboxylic Acids / Q000138:chemical synthesis*; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000138:chemical synthesis*; D009589:Nitrogen Oxides / Q000737:chemistry; D011759:Pyrrolidines / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013454:Sulfoxides / Q000737:chemistry*
chemical_list: C481869:4-amino-pyrrolidine-3-carboxylic acid; D000935:Antifungal Agents; D002264:Carboxylic Acids; D009589:Nitrogen Oxides; D011759:Pyrrolidines; D013454:Sulfoxides; C015388:nitrones; D003515:Cycloleucine; C065594:cispentacin