title: Direct synthetic route to functionalized 1,2-azaborinines.
abstract: A new catalytic synthetic route to functionalized 1,2-azaborinines has been developed by the [2+2]/[2+4] cycloaddition reactions of di-tert-butyliminoboranes and alkynes in presence of a rhodium catalyst. The first examples of ferrocene-functionalized azaborinines have been synthesized using this strategy. Moreover, the regioselectivity of this reaction can be controlled by the formation of an intermediate rhodium 1,2-azaborete complex, which results in the isolation of the first azaborinine boronic ester. The isolation of an NH-containing BN isostere by elimination of isobutene from an N(tBu) group under thermolytic conditions has also been achieved. Theoretical studies give further insight into the formation of 1,2-azaborinines and the elimination of isobutene from the N(tBu) group.
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany) http://www-anorganik.chemie.uni-wuerzburg.de/Braunschweig/index.html. h.braunschweig@mail.uni-wuerzburg.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Braunschweig
authors.forename: K
authors.initials: K
authors.lastname: Geetharani
authors.forename: J Oscar C
authors.initials: JO
authors.lastname: Jimenez-Halla
authors.forename: Marius
authors.initials: M
authors.lastname: Schäfer
keywords: boron; cyclization; heterocycles; isosterism; rhodium