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21.1.3.7 Method 7: Reductive Amidation of Ketones (Leuckart Reaction)

DOI: 10.1055/sos-SD-021-00059

Austin, D. J.; Miller, S. M.Science of Synthesis, (20052189.

The Leuckart reduction is the reductive amination of carbonyl compounds using mixtures of formamide, formic acid, or ammonium formate.[‌26‌] The final product in all cases is a formamide 35, which can be converted, after reduction or hydrolysis in basic or acidic media, into a free amine. Despite the utility of this reaction, its mechanism remains uncertain and, for example, both ionic and radical pathways have been proposed. However, the general consensus is that either a N-formylated imine 34 is generated from the carbonyl compound and formamide, or a rate-limiting C---H bond cleavage of formate ion with hydrogen transfer to the carbonyl group occurs giving rise to a secondary alcohol 36. In the second route the alcohol is then solvolyzed by formamide to give the N-unsubstituted amide 35 (Scheme 18).[‌27‌‌30‌]

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M8 M8 Meeeeeeeeeee (°M) Meeeee (%) Mee
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Me Me 888 88 (88) [‌88‌,‌88‌]
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8,8-(MeM)8M8M8 8,8-(MeM)8M8M8MM8 888 88 (88)e [‌88‌,‌88‌]

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Meeeeeeeee 88; Meeeeee Meeeeeeee:[‌88‌,‌88‌]

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References


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