A Multistep Synthesis Featuring Classic Carbonyl Chemistry for the Advanced Organic Chemistry Laboratory

A multistep synthesis of 5-isopropyl-1,3-cyclohexanedione is carried out from three commodity chemicals. The sequence involves an aldol condensation, Dieckmann-type annulation, ester hydrolysis, and decarboxylation. No purification is required until after the final step, at which point gravity column chromatography provides the desired product in good overall yield. This synthesis sequence allows students to put into practice many of the fundamental acid- and base-catalyzed transformations of carbonyls presented in the second semester of a traditional introductory organic chemistry sequence. Importantly, this synthesis has been optimized to fit entirely within a series of five 4 h laboratory periods and requires no specialized equipment. Furthermore, the intermediates and product of the synthesis exhibit proton NMR spectra that illustrate many important concepts in introductory spectroscopic analysis.