title: From C,N- and N,N-chelated chloroboranes to substituted 1H-2,1-benzazaboroles and 1H-pyrrolo[1,2-c][1,3,2]diazaborolidines: a straightforward route to five-membered rings containing the B-N or N-B-N moiety.
abstract: A set of 1H-2,1-benzazaboroles as B-N analogues of 1H-indene and a set of 1H-pyrrolo[1,2-c][1,3,2]diazaborolidines as B-N analogues of 1H-pyrrolizine were prepared via nucleophilic addition of selected alkyl(aryl)lithiums (MeLi, tBuLi or PhLi) to, via N→B intramolecular interactions, the activated imino C[double bond, length as m-dash]N functionality in the structure of C,N- or N,N-chelated chloroboranes. All compounds were characterized by elemental analysis and (1)H, (11)B, (13)C and (15)N NMR spectroscopy, and molecular structures of isolated compounds were on several occasions established by means of single-crystal X-ray diffraction analysis. The presence of three adjacently bonded substituents and their systematic alternation on five-membered C3BN (1H-2,1-benzazaboroles) or C2BN2 (1H-pyrrolo[1,2-c][1,3,2]diazaborolidines) rings allowed us to follow both the influence of the steric repulsion and limitations for the formation of respective annulated heterocyclic systems.
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, CZ - 532 10, Pardubice, Czech Republic. libor.dostal@upce.cz.
authors.forename: Martin
authors.initials: M
authors.lastname: Hejda
authors.forename: Antonín
authors.initials: A
authors.lastname: Lyčka
authors.forename: Roman
authors.initials: R
authors.lastname: Jambor
authors.forename: Aleš
authors.initials: A
authors.lastname: Růžička
authors.forename: Libor
authors.initials: L
authors.lastname: Dostál