The Synthesis of 6-sustituted-2-chloroquinoline-3-carbaldehyde using Vilsmeier-Haack Reaction

The use of formylation reaction as synthetic strategy to form versatile carboxaldehyde intermediates is still of interest, due to both their intrinsic pharmacological properties and chemical reactivity. Formylation reactions have been described for many heterocyclic derivatives, via the intermediate carboxaldehydes, which is mainly formed using using VilsmeierHaack reaction. Despite this versatile importance of vilsmeier Haack reagent and in continuation of our interest in quinoline nucleus, the synthesis of a series of 6-substituted-2-chloroquinoline-3-carbaldehydes (3a-h) was carried out. All the compounds were characterized by IR, 1H NMR spectroscopic studies. The characteristic two peaks of aldehyde in IR and the 1H NMR signals at value 9-11 indicates the formation of quinoline-3-carbaldehyde from the corresponding oximes.