title: Stereoselectivity in formation of oxacephams from 1,3-alkylidene-threitols.
abstract: The [2+2]cycloaddition of CSI to the (Z)-propenyl ethers derived from respective 1,3-methylidene- and 1,3-ethylidene-threitols, contrary to the corresponding erythritol derivatives, is characterized by a low stereoselectivity and a lack of stereospecificity. On the other hand, the alternative method of the oxacepham formation, based on the 4-vinyloxy-azetidinone, proceeds with an excellent stereoselectivity. The CD-spectroscopy offers an attractive tool for determination of the absolute configuration of the bridgehead carbon atom at the 5-oxacepham skeleton.
authors.affiliation: Institute of Organic Chemistry of the Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Borsuk
authors.forename: Barbara
authors.initials: B
authors.lastname: Grzeszczyk
authors.forename: Patrycja
authors.initials: P
authors.lastname: Szczukiewicz
authors.forename: Beata
authors.initials: B
authors.lastname: Przykorska
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Frelek
authors.forename: Marek
authors.initials: M
authors.lastname: Chmielewski