Aldehydes from Bouveault reaction

Extensions of the use of ultrasound in lithiation reactions have been profitable for a variety of reactions. The Bouveault reaction for the synthesis of aldehydes [Eq. (40)] suffers from side reactions and low yields. 

This type of reaction with A N-disubstituted formamides, giving aldehydes, was an early application of Grignard reagents, sometimes known as the Bouveault reaction [A]. Dimethylformamide and N-methylformanilide, PhN(Me)CHO, have been most commonly used, but more recently iV-formylpiperidine and 2-(/V-formylmethylamino)pyridine have been recommended examples are listed in Table 6.5, and a recent example of the traditional procedure follows. It should be noted that these reactions are subject to a number of side-reactions [A]. One useful one is the formation of enamines by elimination from the initial adduct [9] ... 

Turning their attention to the Bouveault reaction, Luche et al. found that aldehydes could be generated from alkyl halides in a one-pot reaction (Scheme 31). 

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