Organic azides are known and utilized in the synthetic organic chemistry as amine precursors, potential sources of nitrenes, dipoles useful in 1,3-dipolar cycloadditions and starting materials of phosphoranes for a long time, and their literature has been overviewed by several authors. On the other hand, there are some special subclasses within the azides which possess peculiar and interesting properties differing from those of the majority and offering extra synthetic possibilities. In this critical review we wish to give an exhaustive overview on the synthesis and synthetic potential of α-azido ketones and related systems, an underestimated group of compounds. The enhanced acidity of the α-hydrogen offers various new synthetic applications including the creation of a new C–C bond, while the joint presence of the carbonyl and vinyl functions of α-azido-α,β-unsaturated ketones results in a special reactivity, too. Chemo- and stereoselectivity issues also represent important points which are discussed in detail. Finally, the usefulness of the titled derivatives in the synthesis of various heterocycles is reviewed (273 references).

Syntheses and transformations of α-azido ketones and related derivatives

Drop it! A highly enantioselective catalytic cascade reaction of α-ketoacids and aldehydes is achieved using the title catalyst and water as the solvent. Fluorescence imaging shows that the catalyst is mainly distributed on the surface of emulsion droplets. Optically active isotetronic acids can be obtained with this method and the emulsion droplets are responsible for the high reactivity and enantioselectivity.

The Synthesis of Chiral Isotetronic Acids with Amphiphilic Imidazole/Pyrrolidine Catalysts Assembled in Oil-in-Water Emulsion Droplets

Synthesis of Polysubstituted Pyridines via a One-Pot Metal-Free Strategy.

Laccase-catalyzed carbon–carbon bond formation: oxidative dimerization of salicylic esters by air in aqueous solution

An Efficient and Environmentally Friendly Method for Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones Catalyzed by Bi(NO3)3 · 5H2O

Synthesis of functionalized acetophenones by [3 + 3] cyclizations of 1,3-bis-silyl enol ethers with 2-acetyl-3-silyloxyalk-2-en-1-ones

Synthesis of isotetronic acids by cyclization of 1,3-bis(trimethylsilyloxy)alk-1-enes with oxalyl chloride

Treatment of γ-azido-β-hydroxyketones with triphenylphosphine resulted, depending on the structural features of the starting materials, in a domino “Staudinger/semi-aza-Wittig/fragmentation” reaction rather than a normal aza-Wittig reaction. 2-Azido-1-hydroxy-1-(2,4-dioxoalkyl)cyclopentanes, readily available by condensation of 1,3-dicarbonyl dianions with 2-azidocyclopentanone, proved to be optimal starting materials for these reactions which afforded 1-(1,3-dioxoalkyl)amino-2-(alkylidene)cyclopentanes.

Domino “Staudinger/Semi-Aza-Wittig/Fragmentation” Reactions of γ-Azido-β-hydroxyketones

Synthesis of 4-alkoxycarbonyl-butenolides by uncatalyzed one-pot cyclization of 1,3-bis(silyloxy)alk-1-enes with oxalyl chloride

Keto−enol tautomerization of 3-formylacetylacetone has been studied by NMR spectroscopy, ab initio, and DFT calculations in the gas phase and continuum solvation. By employing very low temperatures in a freonic solvent, tautomeric and conformational equilibria in the slow exchange regime were analyzed in detail. The β-tricarbonyl compound always adopts a structure with an enolized keto group irrespective of an increasing dielectric constant of the solvent when lowering the temperature of the Freon mixture. This experimentally observed tautomeric distribution of 3-formylacetylacetone is correctly reproduced by continuum solvated DFT calculations.

Rüdiger Dede

Papers

Synthesis of functionalized acetophenones by [3 + 3] cyclizations of 1,3-bis-silyl enol ethers with 2-acetyl-3-silyloxyalk-2-en-1-ones

Synthesis of isotetronic acids by cyclization of 1,3-bis(trimethylsilyloxy)alk-1-enes with oxalyl chloride

Domino “Staudinger/Semi-Aza-Wittig/Fragmentation” Reactions of γ-Azido-β-hydroxyketones

Synthesis of 4-alkoxycarbonyl-butenolides by uncatalyzed one-pot cyclization of 1,3-bis(silyloxy)alk-1-enes with oxalyl chloride

Tautomeric equilibria of 3-formylacetylacetone: low-temperature NMR spectroscopy and ab initio calculations.