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This rearrangement differs from similar isomerizations of carbohydrates, which involve the migration of hydrogen and proceed through discrete enediol intermediates.These include the Lobry–de Bruyn–van Ekenstein transformation, [2] the Heyns [3] and Amadori rearrangements, [4] and the Voight [5] and Bilik [6] reactions. α-hydroxy imines may also undergo the rearrangement, although the ...
The Reformatsky reaction (sometimes transliterated as Reformatskii reaction) is an organic reaction which condenses aldehydes or ketones with α-halo esters using metallic zinc to form β-hydroxy-esters: [1] [2] The Reformatsky reaction. The organozinc reagent, also called a 'Reformatsky enolate', is prepared by treating an alpha-halo ester ...
This property is exploited in the Favorskii rearrangement, where base abstracts first an acidic α-hydrogen and the resulting carbanion then displaces the halogen. In crossed aldol reactions between halo ketones and aldehydes, the initial reaction product is a halohydrin which can subsequently form an oxirane in the presence of base.
In the case of cyclic α-halo ketones, the Favorskii rearrangement constitutes a ring contraction. This rearrangement takes place in the presence of a base, sometimes hydroxide , to yield a carboxylic acid, but usually either an alkoxide base or an amine to yield an ester or an amide , respectively. α,α'-Dihaloketones eliminate HX under the ...
The CBS reduction has proven to be an effective and powerful method to reduce a wide range of different types of ketones in both a stereoselective and chemoselective manner. Substrates include a large variety of aryl-aliphatic, di-aliphatic, di-aryl, α,β unsaturated enone and ynone systems, as well as ketones containing heteroatoms.
The Buchner–Curtius–Schlotterbeck reaction is the reaction of aldehydes or ketones with aliphatic diazoalkanes to form homologated ketones. [1] It was first described by Eduard Buchner and Theodor Curtius in 1885 [2] and later by Fritz Schlotterbeck in 1907. [3]
The usual way of doing this is from the relevant oxime, via the Neber rearrangement. [ 5 ] [ 6 ] The original Knorr synthesis employed two equivalents of ethyl acetoacetate , one of which was converted to ethyl 2-oximinoacetoacetate by dissolving it in glacial acetic acid , and slowly adding one equivalent of saturated aqueous sodium nitrite ...
The alpha-diazoketone (RC(O)CHN 2) product undergoes the metal-catalyzed Wolff rearrangement to form a ketene, which hydrates to the acid. [ 16 ] [ 17 ] [ 4 ] The rearrangement leaves untouched the stereochemistry at the carbon alpha to the acid chloride.