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Please login to access the full content or check if you have access via2.5.6.2.1 Asymmetric Direct Reductive Amination of Ketones with Ammonium Formate
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Xu, L.; Wu, X.; Xiao, J., Science of Synthesis: Stereoselective Synthesis, (2011) 2, 293.
The reduction of C=O compounds to amines using ammonium formate or formamide is known as the Leuckart–Wallach reaction.[144,145] There are a few studies that have demonstrated the effect of metal catalysis on the reaction.[146–148] In particular, a ruthenium catalyst with chiral diphosphine ligand 76 shows good activity, chemoselectivity, and enantioselectivity in the asymmetric direct reductive amination of aryl ketones, with the best enantiomeric excesses being obtained with 5–10 equivalents of ammonium formate in ammonia/methanol (15–25%) at temperatures between 60 and 85 °C (Scheme 45).[131] N-Formylamines are the main product of the asymmetric direct reductive amination, hydrolysis of which releases the free amines (e.g., 77). The addition of ammonia enhances the enantioselectivity but decreases the reaction rate, and aqueous ammonia increases the yield of the alcohol byproduct. However, the reduction leads to low enantiomeric excesses for aliphatic ketones, such as octan-2-one (24% ee) and 2-methylcyclohexanone (64% ee).
Meeeee 88 Meeeeeeeee Meeeee Meeeeeeee Meeeeeeee ee Meeeeee eeee Meeeeeee Meeeeee[888]
Me8 | M8 | Meee (e) | ee (%) | Meeee (%) | Mee |
---|---|---|---|---|---|
Me | Me | 88 | 88 | 88 | [888] |
Me | Me | 88 | 88 | 88 | [888] |
8-Mee | Me | 88 | 88 | 88 | [888] |
8-Mee | Me | 88 | 88 | 88 | [888] |
8-MeMM8M8 | Me | 88 | 88 | 88 | [888] |
8-MeM8M8 | Me | 88 | 88 | 88 | [888] |
8-MeM8M8 | Me | 88 | 88 | 88 | [888] |
8-M8MM8M8 | Me | 88 | 88 | 88 | [888] |
8-eeeeeeee | Me | 88 | 88 | 88 | [888] |
8-eeeeeeee | Me | 88 | 88 | 88 | [888] |
Meeeeeeeeeee Meeeeeeee
Meeeee Meeeee 88; Meeeeee Meeeeeeee eee Meeeeeeeee Meeeee Meeeeeeee Meeeeeeee ee Meeeeee eeee Meeeeeee Meeeeee:[888]
[MeMe8(88)(MMM)e][888] (88 ee, ee. 88 µeee), eeeeee (8 eeee), eee MM8MMM8 (8.88 e, 88 eeee) eeee eeeeee ee e 88-eM Mee eeeeeeee eeee eeeee eeeee. Meeeeee eeeeeeeee MM8 ee eeeee MeMM (88–88%, 88 eM) eee eeeee, eee eeee eee eeee eee eeeeee eeeee eeeee eee eeeeeee ee 88 °M eee eee eeee eeeeeeeee ee Meeeee 88. Meeeeeeee eeeeeee ee eee eeeeeeee eeeeeeeeee, eee eeeeeee eee eeeeeeeee ee MeMM (88 eM), eee 8 M MMe (8 eM) eee eeeee. Mee eeeeeee eee eeeeee ee eeeeee eee 8 e ee eeeeeeeee eee eeeeee eeeeeeeeee, eee eeee eeeeee ee ee, eeeeeee eeee M8M (88 eM), eee eeeeeeeee eeee Me8M ee eeeeee eee eeeeeeeee eeeeee. Mee eeeeeee eeeee eee eeee eeeeeeee ee eeeeeeee ee e 88% MM8 eeee (8 eM), eee eeeeeeeee eeee MM8Me8 (8 × 8 eM). Mee eeeeeeee eeeeeee eeeeeeee eeee eeeee (Me8MM8) eee eeeeeeeeeeee ee eeeeee eee eeeee eeeee, eeeee eee eeeee ee ee eeee ee 8M MMM eeeeeeeeeeee. Mee ee eee eeeeeeeeee ee MM eeeeeeee ee eee eeeeeeeeeeeee eeeeeeeee eeee e eeeeee eeeeee (Meeeeeeee, MM Meeeeeee-MMM MM).
References
[131] | Meeeeee, M.; Meeeeeeee, M. M., Meeee. Meee., (8888) 888, 8888; Meeee. Meee. Mee. Me., (8888) 88, 8888. |
[144] | Mee, M.; Meeeeeeeeee, M. M., Meeeeeeee, (8888), 88. |
[145] | Meeee, M. M., Mee. Meeee. (M. M.), (8888) 88, 888. |
[146] | Meeeeeee, M.; Mee, M.; Meeeeee, M.; Meeeee, M.; Meeeeeeee, M., M. Mee. Meee., (8888) 88, 8888. |
[147] | Meeeeee, M. M.; Meeee, M. M., M. Me. Meee. Mee., (8888) 88, 8888. |
[148] | Mee, M. M., MM 8 888 888, (8888); Meee. Meeee., (8888) 888, 88888. |
[149] | Meeeeeee, M.; Meeeeeee, M.; Meeeee, M.; Meeeee, M., Mee. Meeee., Meee. Mee. MM, (8888), 888. |