Friedländer synthesis

The Friedländer synthesis is a chemical reaction of 2-aminobenzaldehydes[1] with ketones to form quinoline derivatives.

[2][3] It is named after German chemist Paul Friedländer (1857–1923).

In the first mechanism 2-amino substituted carbonyl compound 1 and carbonyl compound 2 react in a rate-limiting step to aldol adduct 3.

This intermediate loses water in an elimination reaction to unsaturated carbonyl compound 4 and then loses water again in imine formation to quinoline 7.

In the second mechanism the first step is Schiff base formation to 5 followed by Aldol reaction to 6 and elimination to 7.