The cyclization of 2,3-dihalopyridines with readily available imines provides a convenient and regioselective approach to 4- and 7-azaindoles. The regioselectivity can be controlled by the choice of the halogen atoms at the pyridine ring (chlorine versus bromine).

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Synthesis of triazolo-cyclobutane nucleosides analogs is reported. These molecules have been obtained by a short and efficient sequence involving a click azide-alkyne cycloaddition following by cis-hydroxylation in the key step.

The base promoted Pd-catalyzed cyclization of 2-bromo-3-chloropyridine with a range of diarylimines affords 4-azaindoles. On the other hand, 3-bromo-2-chloropyridine reacts under similar conditions to give 7-azaindoles, regioselectively. -(PHAM, N. N.; DANG, T. T.; NGO, N. T.; VILLINGER, A.; EHLERS, P.; LANGER*, P.; Org. Biomol. Chem. 13 (2015) 21, 6047-6058, http://dx.doi.org/10.1039/C5OB00720H ; Inst. Chem., Univ. Rostock, D-18059 Rostock, Germany; Eng.) -Mais 37-192