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Although examples of enantioselective α-ketol rearrangements starting from achiral α-hydroxy ketones are fairly limited, a number of examples of 1,2-asymmetric induction (due to stereoelectronic factors) have been observed. In one example of an enantioselective process, use of nickel(II) diacetoacetonate and pybox provided 4 in 34% ee. [11] (4)
α-hydroxy ketones give positive Tollens' and Fehling's test. Some acyloins rearrange with positions swapped under the influence of base in the Lobry–de Bruyn–van Ekenstein transformation; A similar reaction is the so-called Voigt amination [6] where an acyloin reacts with a primary amine and phosphorus pentoxide to an α-keto amine: [7]
Alpha-hydroxy ketones are also called acyloins. [1] They are commonly formed by condensation or reductive coupling of two carbonyl (C=O) compounds or oxidation of ketones. The simplest such compound is hydroxyacetone. If the alcohol is primary, alpha-hydroxy ketones give a positive Fehling's test. Beta-hydroxy ketones are a type of aldol.
The net reaction between an aldehyde (or an alpha-hydroxy-ketone) and the copper(II) ions in Benedict's solution may be written as: RCHO + 2 Cu 2+ + 5 OH − → RCOO − + Cu 2 O + 3 H 2 O. The hydroxide ions in the equation forms when sodium carbonate dissolves in water. With the citrate included, the reaction becomes:
The following examples represent only a small portion of syntheses that highlight the use of the Rubottom oxidation to install an important α-hydroxy functionality. Some of the major features of the following syntheses include the use of buffered conditions to protect sensitive substrates and the diastereoselective installation of the α ...
Alpha-ketoglutarate-dependent hydroxylases are a major class of non-heme iron proteins that catalyse a wide range of reactions. These reactions include hydroxylation reactions, demethylations, ring expansions, ring closures, and desaturations. [1] [2] Functionally, the αKG-dependent hydroxylases are comparable to cytochrome P450 enzymes.
It is an α-hydroxyketone, also called a ketol, and is the simplest hydroxy ketone structure. It is a colorless, distillable liquid. It is a colorless, distillable liquid. Preparation
Halogenation of α,β-unsaturated ketone [3] On α,β-Unsaturated ketones or enones, it's possible to halogenate with iodine selectively on the more saturated alpha on the ketone selectively over the unsaturated side. Iodine is preferred due to it being more reactive than alkyl bromides which makes this reaction quite useful. [3]