SYNTHESIS OF AROMATIC HETEROCYCLES CONSTRUCTION OF THE RING SKELETON Carbonyl condensation type reactions Cycloadditions with 1,3-dipoles with ortho-quinodimethanes (DA type react.) Nitrene insertion Carbonyl condensations
Strategy a) - 5-membered rings Pyrrole (Paal-Knorr Synthesis s 255) Furan Thiophene
Strategy a) - 6-membered rings
Strategy b 5-membered rings 6-membered rings Enol (or phenol) Enamin (or anilin)
1,3-Dipolar Cycloaddition Only 5-membered rings Alkene / alkyne Ex. ozonolysis
Cycloaddition with ortho-Quinodimethanes Electrocyclic ring opening
Nitrene Insertion Generation of nitrenes
React. of nitrenes
Nitrene insertion - Heterocyclic synthesis