Glycidic rearrangement

Benzilic acid rearrangement Benzoin reaction (condensation) Blanc chloromethylation reaction Bouveault-Blanc reduction Bucherer hydantoin synthesis Bucherer reaction Cannizzaro reaction Claisen aldoi condensation Claisen condensation Claisen-Schmidt reaction. Clemmensen reduction Darzens glycidic ester condensation Diazoamino-aminoazo rearrangement Dieckmann reaction Diels-Alder reaction Doebner reaction Erlenmeyer azlactone synthesis Fischer indole synthesis Fischer-Speior esterification Friedel-Crafts reaction... 

Other methods for the preparation of cyclohexanecarboxaldehyde include the catalytic hydrogenation of 3-cyclohexene-1-carboxaldehyde, available from the Diels-Alder reaction of butadiene and acrolein, the reduction of cyclohexanecarbonyl chloride by lithium tri-tcrt-butoxy-aluminum hydride,the reduction of iV,A -dimethylcyclohexane-carboxamide with lithium diethoxyaluminum hydride, and the oxidation of the methane-sulfonate of cyclohexylmethanol with dimethyl sulfoxide. The hydrolysis, with simultaneous decarboxylation and rearrangement, of glycidic esters derived from cyclohexanone gives cyclohexanecarboxaldehyde. 

Apart from the reaction of cyclohexanecarboxylic acid with methyllithium, cyclohexyl methyl ketone has been prepared by the reaction of cyclohexylmagnesium halides with acetyl chloride or acetic anhydride and by the reaction of methylmagnesium iodide with cyclohexanecarboxylic acid chloride. Other preparative methods include the aluminum chloride-catalyzed acetylation of cyclohexene in the presence of cyclohexane, the oxidation of cyclohexylmethylcarbinol, " the decarboxylation and rearrangement of the glycidic ester derived from cyclohexanone and M)utyl a-chloroj)ropionate, and the catalytic hydrogenation of 1-acetylcycIohexene. "... 

Photochemically induced ring cleavage reactions have also been reported in a,/i-epoxydiazomethyl ketones" and in a,/f-epoxy esters (glycidic esters).100 Two separate photoreactions are involved, however, in the rearrangement of phenyl epoxycinnamate (118) to the flavone (119), as shown in Scheme 7.101... 

Isomerization of substituted styrene oxides allows the synthesis of aldehydes in high yields726 [Eq. (5.275)]. Cycloalkene oxides do not react under these conditions, whereas 2,2,3-trimethyloxirane gives isopropyl methyl ketone (85% yield). Isomerization of oxiranes to carbonyl compounds is mechanistically similar to the pinacol rearrangement involving either the formation of an intermediate carbocation or a concerted mechanism may also be operative. Glycidic esters are transformed to a-hydroxy-/3,y-unsaturated esters in the presence of Nafion-H727 [Eq. (5.276)]. 

Burness24, 79 prepared 3-methyl-2-carbomethoxyfuran in 55% yield from jS-ketobutyracetal, with rearrangement of the intermediate glycidic ester ... 

When this epoxide product is treated with aqueous acid, a rearrangement of the carbon skeleton occurs. This is the glycidic acid rearrangement, which is named after the product formed in the archetypal reaction. 

The initial product of the decarboxylation tautomerises to give the carbonyl compound. This is called the glycidic acid rearrangement. 

Glycidic ester The reaction in which a glycidic ester (an a,P-epoxycarboxylic ester) rearranges under acidic conditions to give, after heating, an aldehyde. 

Rearrangement of epoxides. An interesting example reported by House is as follows. A benzene solution of the glycidic ester (1) is saturated with BF3 and allowed to stand at room temperature for 30 min. workup alfords the a-keto ester (2) in high yield. 

By analogy with the rearrangement of styrene oxide compounds, more complicated substances, e. g. phenylpyruvic acid methyl ester derivatives, can be synthesized from readily available glycidic acid esters, as shown in Figure 3. These esters can be used as intermediates for herbicides (e. g. the triazinones) and for the synthesis of L-amino acids. 

Figure 3. Rearrangement of glycidic acid esters (R = alkyl, alkoxy, halide, hydroxyl).

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