Hänschs

Hänschs refers to a family of chemical reactions in organic chemistry, most notably the Hänsch pyrrole synthesis and the Hänsch dihydropyridine synthesis. These named reactions are named after the German chemist Arthur Hantzsch.

The Hänsch pyrrole synthesis involves the reaction of an alpha-haloketone with a beta-ketoester in the presence of ammonia or a primary amine. This condensation reaction results in the formation of a substituted pyrrole ring. The specific substituents on the pyrrole are determined by the starting materials used. This reaction is a versatile method for constructing pyrrole derivatives, which are important heterocyclic compounds found in many natural products and pharmaceuticals.

The Hänsch dihydropyridine synthesis is perhaps the more commonly referenced reaction. It involves a multi-component reaction where an aldehyde, two equivalents of a beta-ketoester, and ammonia or a primary amine react to form a 1,4-dihydropyridine derivative. This reaction is often carried out in a single pot. The resulting dihydropyridines are significant as they are the core structure of many calcium channel blocker drugs, used to treat conditions like hypertension and angina. Variations of the Hänsch dihydropyridine synthesis exist, employing different catalysts and conditions to improve yields and modify the products.