Ethyl 2-diazo-4,4,4-trifluoro-3-oxobutanoate: A Valuable Precursor in Organic Synthesis

Abstract

Introducing the CF₃ group into heterocycles is paramount, as it can alter their biological and physicochemical properties due to its unique properties viz., electronegativity, lipophilicity, metabolic stability, and bioavailability. Ethyl 2-diazo-4,4,4-trifluoro-3-oxobutanoate is a valuable precursor for the synthesis of an array of trifluoromethyl heterocycles. This \(\alpha\)-diazo-\(\beta\)-ketoester can be employed in several chemical transformations involving dinitrogen extrusion under catalytic conditions or with retention of the diazo group in the reaction product. The presence of trifluoromethyl group in ethyl diazo-4,4,4-trifluoro-3-oxobutanoate imparts increased electrophilicity and reactivity of the diazo functionality in comparison to non-fluorinated counterparts such as CH₃. In transition-metal-catalyzed reactions, this compound generates metal carbene species as versatile electrophilic intermediates, which can typically be utilized in X-H (X = C, O, S, N, etc.) insertion reactions and ylide formations to afford diverse products. This article summarizes the synthetic utility of ethyl 2-diazo-4,4,4-trifluoro-3-oxobutanoate in accessing trifluoromethylated pyrrole, furan, pyrazole, imidazole, oxazole, thiazole, pyridine, 1,2,4-triazine, 1,4-dioxene, 1,4-oxazine, 1,4-oxathiine, 1,4-dioxine and pyridazine derivatives as well as mechanistic aspects of some reactions.