Synthesis of 1,2-Diketones by the Transition Metal-Catalyst-Free Reaction of α-Oxo Acid Chlorides or Oxalyl Chloride with Organostannanes

Investigation on the Synthesis, Application and Structural Features of Heteroaryl 1,2-Diketones

A set of unsymmetrical heteroaryl 1,2-diketones were synthesized by a heteroarylation/oxidation sequence with up to 65% isolated yields. Palladium catalyst XPhos Pd G4 and SeO₂ were the key reagents used in this methodology, and microwave irradiation was utilized to facilitate an efficient and ecofriendly process. The application of heteroaryl 1,2-diketones is demonstrated through the synthesis of an unsymmetrical 2-phenyl-3-(pyridin-3-yl)quinoxaline (5a) from 1-phenyl-2-(pyridin-3-yl)ethane-1,2-dione (4a). The lowest energy conformations of 4a and 5a were located using Density Functional Theory (DFT) at the M06-2X/def2-TZVP level of theory. Two lowest energy conformations of 4a differ with respect to the position of the N atom in the pyridyl ring and 0.27 kcal/mol energy difference between them corresponds to 60.4 and 39.6% at 50 °C in toluene. Four lowest energy conformations for 5a have the energy differences of 0.01, 0.03 and 0.07 kcal/mol that corresponds to 26.0, 25.7, 24.9 and 23.4%, respectively. A comparison of 4a and 5a to the less hindered analogs (oxalyl chloride and oxalic acid) is used to investigate the structural features and bonding using Natural Bond Orbital (NBO) analysis.

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

This study investigates a synthetic sequence for the preparation of 1,2-diketone products. The sequence avoids oxidative conditions and instead employs reliable transformations including the Horner-Wadsworth-Emmons and addition of Grignard reagents to N-methyl-N-methoxy (Weinreb) amide intermediates. The reaction sequence is suitable for the synthesis of nonsymmetric aliphatic and aryl substituted derivatives.

Nitroaldol (Henry) reaction of 2-oxoaldehydes with nitroalkanes as a strategic step for a useful, one-pot synthesis of 1,2-diketones

The nitroaldol (Henry) reaction of 2-oxoaldehydes with a variety of nitroalkanes, under basic heterogeneous conditions and microwave irradiation, affords 1,2-diketones in a one-pot way.

Cobalt(ii) catalyzed C(sp)–H bond functionalization of alkynes with phenyl hydrazines: facile access to diaryl 1,2-diketones

A cobalt acetylacetonate catalyzed oxidative diketonation of alkynes via C(sp)–H bond functionalization has been described. Its application to the synthesis of imidazoles has also been demonstrated.

Synthesis of benzil derivatives via oxidation of alkynes catalyzed by Pd–Fe3O4 heterodimer nanocrystals

An efficient, iterative, catalytic, Wacker-type oxidation of alkynes to 1,2-diketones using a Pd–Fe₃O₄ heterodimer nanocrystalline catalyst has been developed.