Formation of Aldehydes and Ketones by Reduction of Phenols, Carboxylic Acids and Deriatives, and Nitriles

Abstract

Phenols and Derivatives Acylsilanes Carboxylic Acids Acid Halides Anhydrides Esters Thioesters Selenoesters Lactones Amides and Imides Nitriles and Acyl Nitriles 4,5‐Dihydrooxazoles and 2‐Imidazolines

Partial reductions of carboxylic acids and their derivatives to aldehydes

“…Two plausible mechanistic pathways were proposed (Scheme 6b). Sterically guided selective oxidative addition of mixed anhydrides (22) to a Pd(0) catalyst afforded acyl palladium(II) intermediates (23), which underwent σ-bond metathesis with hydrosilanes to form acylpalladium hydrides (24). Finally, reductive elimination of 24 gave aldehydes.…”

“…Besides, numerous methods including metal hydride reductions are also accessible. The advances before 2010 have been summarised by Larock, Dubrovskiy, and Markina, 24 and will not be discussed herein.…”

“…Some of the reagents, for example, DIBAL-H, have been proven to be very reliable, and have been widely used by chemists to synthesize aldehydes from nitriles. [13][14][15][16][17][18][19][20][21][22][23][24] Since 2010, only two new reductions associated with this subtopic are available.…”

“…96 The advances from 1995 to 2010 have been summarized by Arnott, 23 Larock and coworkers. 24 Recently in 2012, Brookhart and coworkers reported an iridium-catalyzed efficient reduction of inert esters to aldehydes (Scheme 37). 97 The methyl or ethyl esters, which were inactive in Chatani's reduction, 41 were smoothly hydrosilylated and subsequently hydrolysed to the corresponding aldehydes.…”

“…23 In a most recent review in 2018, Larock, Dubrovskiy, and Markina gave a comprehensive and detailed summary of the methods for reductive synthesis of aldehydes. 24 However, the references cited in the most recent two reviews were overwhelmingly published before 2010. In 2018, the centenary of the discovery of Rosenmund reduction, Bergman and coworkers briefly yet insightfully commented on the methodologies for synthesizing aldehydes by reduction since 1918, and highlighted the improved methods based on modern strategies such as transition-metal catalysis and photocatalysis.…”