Room-Temperature Coupling/Decarboxylation Reaction of α-Oxocarboxylates with α-Bromoketones: Solvent-Controlled Regioselectivity for 1,2- and 1,3-Diketones

Abstract

A transition-metal-free and room-temperature coupling/decarboxylation reaction between α-oxocarboxylates and α-bromoketones is reported herein. It represents the first mild and regioselective synthesis of either 1,2- or 1,3-diketones from the same starting materials. Notably, the regioselectivity is simply controlled by solvents. The preliminary experimental data and DFT calculations suggest sequential Darzens-type coupling, alkaline hydrolysis, KOH-promoted oxirane opening and decarboxylation in one pot. This method is efficient for the synthesis of α,β-epoxy-γ-butyrolactone and curcuminoids.

A Nonoxidative Sequence for the Preparation of 1,2-Diketone Derivatives Using Aldehyde and Organometallic Building Blocks

“…The combined organic layers were washed with brine (10 mL), dried over Na 2 SO 4 , filtered, and concentrated in vacuo. The resulting residue was purified by flash column chromatography on silica gel (gradient elution: 10% CH 2 Cl 2 to 60% CH 2 Cl 2 in hexanes) to afford a 7:5 keto/enol mixture of diketone 14a (5.4 mg, 19% yield) as a colorless oil: TLC (30% CH 2 Cl 2 in hexanes): R f : 0.31 (UV/CAM); spectral data for diketone 14a are in agreement with published data …”

Highly Modular Synthesis of 1,2-Diketones via Multicomponent Coupling Reactions of Isocyanides as CO Equivalents

“…Multicomponent one-pot reactions offer efficiency and sustainability in organic synthesis and are increasingly being employed to build complexity in pharmaceutical and fine chemical synthesis. − Of particular value are highly modular unions of widely available building blocks to access novel structural motifs. 1,2-Diketones are useful intermediates in synthetic organic chemistry, often used in the synthesis of medicinally relevant heterocycles, such as imidazoles, pyrazines, and quinoxalines as well as natural products. − They are also used in materials chemistry , and as ligands for various metal complexes. − Despite their widespread synthetic utility, 1,2-diketone synthesis is typically achieved via lengthy linear sequences and oxidative protocols. − These approaches are often limited to (symmetrical) dibenzylic 1,2-diketones and suffer poor compatibility with heteroaryl substrates, preventing efficient access to large libraries of these highly versatile derivatives (Scheme ).…”

Tris(pentafluorophenyl)borane‐Catalyzed Oxygen Insertion Reaction of α‐Diazoesters (α‐Diazoamides) with Dimethyl Sulfoxide

“…α ‐Ketoesters represent a useful class of precursors for the construction of numerous important organic compounds through functional group transformations, [1] such as chiral α ‐hydroxy esters, [2a] 2,3‐dihydropyran‐4‐one derivatives, [2b] 1,2‐ and 1,3‐diketones, [2c] oxetane derivatives [2d] and so on. Given their extensive applications, various synthetic methods for constructing α ‐ketoesters and their derivatives have been established [3] .…”