title: Synthesis and reactivity of (C6F5)3B-N-heterocycle complexes. 1. Generation of highly acidic sp3 carbons in pyrroles and indoles.
abstract: The reaction of pyrroles and indoles with B(C(6)F(5))(3) and BCl(3) produces 1:1 B-N complexes containing highly acidic sp(3) carbons, for example, N-[tris(pentafluorophenyl)borane]-5H-pyrrole (1) and N-[tris(pentafluorophenyl)borane]-3H-indole (2), that are formed by a new formal N-to-C hydrogen shift, the mechanism of which is discussed. With some derivatives, restricted rotation around the B-N bond and/or the B-C bonds was observed by NMR techniques, and some rotational barriers were calculated from experimental data. The acidity of the sp(3) carbons in these complexes is shown by their ability to protonate NEt(3), with formation of pyrrolyl- and indolyl-borate ammonium salts. The driving force for this reaction is given by the restoration of the aromaticity of the heterocycle.
authors.affiliation: Basell Polyolefins, Centro Ricerche G. Natta, I-44100 Ferrara, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Guidotti
authors.forename: Isabella
authors.initials: I
authors.lastname: Camurati
authors.forename: Francesca
authors.initials: F
authors.lastname: Focante
authors.forename: Luca
authors.initials: L
authors.lastname: Angellini
authors.forename: Gilberto
authors.initials: G
authors.lastname: Moscardi
authors.forename: Luigi
authors.initials: L
authors.lastname: Resconi
authors.forename: Rino
authors.initials: R
authors.lastname: Leardini
authors.forename: Daniele
authors.initials: D
authors.lastname: Nanni
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Mercandelli
authors.forename: Angelo
authors.initials: A
authors.lastname: Sironi
authors.forename: Tiziana
authors.initials: T
authors.lastname: Beringhelli
authors.forename: Daniela
authors.initials: D
authors.lastname: Maggioni