Lithium Bouveault reaction

The Bouveault reaction is the preparation of an aldehyde by a one pot reaction between an organic halide and lithium metal in dimethylformamide. Ultrasound has been found to markedly enhance this reaction when it is performed in tetrahydrofuran [93]. Use of an ultrasonic bath at 10-20 °C affords short reaction times of between 5 and 15 min and generates yields in the range 70-88%. Using this methodology the conversion of 1-bromobutane to pentanal (88%) can be achieved in only 5 minutes. This must be contrasted with the yield of less than 10 % which is obtained under the normal stirred conditions in the same time period. This result confirms that the effect of irradiation goes beyond mere agitation (Eq. 3.11). 

Formylation of an alkyllithium (1, 280).1 Formylation of an alkyllithium or a Grignard reagent with DMF (Bouveault reaction) is generally unsatisfactory because of side reactions. However, sonication of the mixture of an alkyl or aryl halide, lithium, and DMF substantially improves the rate and the yield. The method is applicable to primary, secondary, and tertiary bromides or chlorides. Typical yields are in the range 65-85%. 

The title aldehyde was prepared as a hydrate by a modified Bouveault reaction. This procedure is usually carried out with magnesium or lithium, and sonication greatly enhances its yields. 0 In the present case, optimal results are obtained with an aluminum-tin couple. 

Sonication of aryl halides with lithium with low intensity ultrasonic gives organolithium reagents. These are used in Bouveault reaction giving higher yields of aldehydes (Scheme 27) than the traditional methods." ... 

Ultrasonic irradiation of alkyl or aryl halides in the presence of lithium and dimethylformamide gives good yields of the aldehyde. The irradiation gives improvements over the classical Bouveault reaction in yield and in the rate of the reaction. The formylation is successful for primary, secondary, and tertiary halides (bromides or chlorides), as well as aryl halides. An alternative approach... 

Sodium metal in conjunction with a protic solvent such as an alcohol is sometimes used as a less expensive substitute for lithium aluminum hydride for reducing esters to alcohols in an industrial setting. This is the Bouveault-Blanc reaction. A modem version of this old reaction employs sodium-in-silica-gel (Na-SG), a safe fi ee-flowing powder, instead of the bulk metal (B. S. Bodnar, P. F. Vogt, J. Org. Chem. 2009, 74, 2598-2600) ... 

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