Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines

Abstract

The first transition-metal-free catalytic protocol for controlled reduction of amide functions using cheap and bench-stable hydrosilanes as reducing agents has been established. By altering the hydrosilane and solvent, the new method enables the selective cleavage of unactivated C−O bonds in amides and allows the C−N bonds to selectively break via the deacylated cleavage. Overall, this novel process may offer a versatile alternative to current methodologies employing stoichiometric metal systems for the controlled reduction of carboxamides.

Hydrosilylation and hydroboration in a sustainable manner: from Earth-abundant catalysts to catalyst-free solutions

“…Most recently, the same research group also reported a controlled reduction of amides by using different hydrosilanes (Scheme 11). 79 This method is compatible with a wide range of functional groups, including halides, alkoxy, and trifluoromethyl moieties. All of them can be reduced in a controlled way to deliver corresponding tertiary or secondary amines in extremely high yields, depending on the type of reductant.…”

Ru-Catalyzed ortho-Selective Diborylation of 2-Arylpyridines toward the Construction of π-Conjugated Functions

“…Mp: 172−175 °C. 1 H NMR (400 MHz, CDCl 3 , 20 °C): δ 8.80 (d,J = 8.2 Hz,1H),8.67 (d,J = 5.4 Hz,1H),7.93 (d,J = 7.8 Hz,1H),7.78 (d,J = 7.3 Hz,2H), 7.36 (dd, J = 13.7 Hz, J = 6.6 Hz, 2H), 1.40 (s, 24H). 13 C{ 1 H} NMR ( 101MHz, CDCl 3 , 20 °C): δ 157.…”

“…1 H NMR (400 MHz, CDCl 3 , 20 °C): δ 8.71 (d,J = 8.2 Hz,1H),8.63 (d,J = 5.3 Hz,1H),1H),7.79 (s,2H),1H), 1.41 (s, 24H), 1.36 (s, 9H). 13 C{ 1 H} NMR (101 MHz, CDCl 3 , 20 °C): δ 158.…”

“…11 B NMR (192 MHz, CDCl 3 , 20 °C): δ 22.4, 21.3. 13 C{ 1 H} NMR (101 MHz, CDCl 3 , 20 °C): δ 164.5 (d,J = 254.1 Hz),156.9,142.7,142.1,137.5,122.3,121.6 (d,J = 18.9 Hz) 2-(2,6-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-(trifluoromethyl)phenyl)pyridine (2g). Purification by neutral aluminum oxide column chromatography using ethyl acetate/ petroleum ether (1:10 to 1:1, v/v) gave a pale yellow oil, 0.34 g, 71%.…”

“…Mp: 150−152 °C. 1 H NMR (400 MHz, CDCl 3 , 20 °C): δ 8.73 (d,J = 5.4 Hz,1H),8.47 (d,J = 8.2 Hz,1H),1H),8.23 (s,1H),1H), 7.84 (dd, J = 6.4 Hz, J = 2.9 Hz, 1H), 2H),7.36 (dd,J = 9.4 Hz,J = 3.5 Hz,1H),1.53 (s,12H),1.44 (s,12H). 11 B NMR (192 MHz, CDCl 3 , 20 °C): δ 22.3.…”