Regioselective Bromination of Fused Heterocyclic N-Oxides

Abstract

A mild method for the regioselective C2-bromination of fused azine N-oxides is presented, employing tosic anhydride as the activator and tetra-n-butylammonium bromide as the nucleophilic bromide source. The C2-brominated compounds are produced in moderate to excellent yields and with excellent regioselectivity in most cases. The potential extension of this method to other halogens, effecting C2-chlorination with Ts(2)O/TBACl is also presented. Finally, this method could be incorporated into a viable one-pot oxidation/bromination process, using methyltrioxorhenium/urea hydropgen peroxide as the oxidant.

Regioselective trifluoromethylation of N-heteroaromatic compounds using trifluoromethyldifluoroborane activator

“…N-oxidation and O-acylation or -sulphonylation of the resulting N-oxides are a well-established method for activating N-heteroaromatics as electrophiles 48 . When this method is applied to trifluoromethylation of pyridine derivatives, however, the reaction does not proceed at all.…”

Aliphatic bromination with tetrabromomethane on immobilized copper complexes

“…8, curve 2) has a distinct extremum. Such a shape of the curve can be explained as follows: the initial increase in the yield to a maximum is due to the fact that alcohols are not only involved in the formation of mixedligand complexes with copper halide derivatives or/and formation of the solvation shell around the polar moiety of the catalyst, but also can directly participate in chain initiation (10) and propagation (11) [22,23]:…”

“…Bromination of organic substrates still remains an important method for preparing a broad range of products and intermediates for organic synthesis [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. This study is devoted to the design of catalytic systems with covalently attached copper complexes for bromination of alkanes with tetrabromomethane and selection of optimal conditions for these processes using the reaction of decane as an example:…”

Structural Characterization of 6-Bromo-5-nitroquinoline-1-oxide: A Quantum Chemical Study and XRD Investigations

“…Aromatic N-oxides contain an oxygen atom bound to a nitrogen atom of the heteroaromatic via a semipolar bond. The N-oxide group is a good conductor for introducing a functional group in the position of ortho or para into the nitrogen atom [3,4]. Also, the N-oxide group can demonstrate both electron-donor and electron-acceptor properties depending on the features of the electronic structure of heteroaromatics due to mesomeric structures of Noxide in pyridine cycle [5].…”