Weiss‐Cook Condensation

Abstract The condensation between an α‐dicarbonyl molecule and 2 equivalents of 3‐oxoglutarate (or dialkyl 1,3‐acetonedicarboxylate) in a slightly acidic aqueous media (pH = 5) to form a cis ‐bicyclo[3.3.0]octane‐3,7‐dione derivative after acidic hydrolysis and decarboxylation is known as the Weiss reaction. This reaction is also known as the Weiss–Cook condensation because of the contribution by Weiss and his student Cook for the synthesis of multicyclic polyquinane systems. The present study addresses all the features of this reaction and compare it with the Diels‐Alder reaction. It has been reported that the Weiss–Cook condensation involves a series of thermodynamic equilibria during the cyclization that favor the cis isomer over its trans isomer. It has also been observed that the Weiss–Cook condensation also takes place under basic conditions. This reaction has been used for the syntheses of a series of fused molecules (e.g., polyquinanes and polyquinenes), which are otherwise prepared by much more complicated procedures.