title: Carbohydrate-auxiliary assisted preparation of enantiopure 1,2-oxazine derivatives and aminopolyols.
abstract: An approach to enantiopure hydroxylated 2H-1,2-oxazine derivatives is presented utilizing the [3 + 3] cyclisation of lithiated alkoxyallenes and an L-erythrose-derived N-glycosyl nitrone as precursors. This key step proceeded only with moderate diastereoselectivity, but allowed entry into both enantiomeric series of the resulting 3,6-dihydro-2H-1,2-oxazines. Their enol ether double bond was then subjected to a hydroboration followed by an oxidative work-up, and finally the auxiliary was removed. The described three-step procedure enabled the synthesis of enantiopure hydroxylated 1,2-oxazines. Typical examples were treated with samarium diiodide leading to enantiopure acyclic aminopolyols. We also report on our attempts to convert these compounds into enantiopure hydroxylated pyrrolidine derivatives.
authors.affiliation: Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany ; Department of Organic and Applied Chemistry, University of Łódź, Tamka 12, PL-91-403 Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Jasiński
authors.forename: Dieter
authors.initials: D
authors.lastname: Lentz
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Reissig