Reduction of Amides to Amines with Pinacolborane Catalyzed by Heterogeneous Lanthanum Catalyst La(CH₂C₆H₄NMe₂-o)₃@SBA-15

Abstract

Hydroboration of amides is a useful synthetic strategy to access the corresponding amines. In this contribution, it was found that the supported lanthanum benzyl material La­(CH2C6H4NMe2-o)3@SBA-15 was highly active for the hydroboration of primary, secondary, and tertiary amides to amines with pinacolborane. These reactions selectively produced target amines and showed good tolerance for functional groups such as −NO2, −halogen, and −CN, as well as heteroatoms such as S and O. This reduction procedure exhibited the recyclable and reusable property of heterogeneous catalysts and was applicable to gram-scale synthesis. The reaction mechanisms were proposed based on some control experiments and the previous literature. This is the first example of hydroborative reduction of amides to amines mediated by heterogeneous catalysts.

Synthesis and catalytic performance of nickel phosphinite pincer complexes in deoxygenative hydroboration of amides

“…at 40 °C), presenting a rare example of a system for catalytic deoxygenation of 2° amides under mild conditions. 6 f ,9–12 On the other hand, reactions of N -phenylbenzamide and N -phenylpropanamide with HBPin cata-lyzed by 1-BF 4 , 3-Me , 3-BH 4 , 2-OPh , 3-OPh , and 3-OAc were found to be more sluggish showing conversions in the range 10–67% (Scheme 7, entries 16–21).…”

“…6 f However, the advantages of deoxygenative hydroboration of amides in terms of the substrate scope and selectivity have been already exemp-lified with several d-block transition metal systems operating under rather mild conditions (<100 °C). 9–12 Nonetheless, only scarce examples of abundant base-metal catalysts (Mn, Fe, Co, and Ni) for deoxygenative hydroboration of amides have been reported (Fig. 1).…”

s-Block Metal Catalysts for the Hydroboration of Unsaturated Bonds

“…While the first s-block magnesium-catalyzed hydroboration of esters and amides was reported by Sadow in 2014 and 2015 ( 75 ), the first example using a lanthanum-based precatalyst ( 120 ) was reported in 2019 by the same author . Since then, other La-based complexes have been reported as active precatalyst toward esters and amides. − When comparing La with Mg complexes, we can observe that both types of complexes exhibit similar reactivity (Scheme ).…”

Copper Immobilized over 2D Hexagonal SBA-15 for Electrochemical and Colorimetric Sulfite Sensing

“…Among the mesoporous silica family of materials, SBA-15 with 2D hexagonally arranged ordered mesoporous silica has attracted special attention over the years due to their high internal surface area, large pore volume, ease of surface functionalization, and high hydrothermal stability . Functionalized SBA-15 materials are largely employed as catalyst supports through hosting metal ions/metallic nanoparticles. , Though transition-metal-grafted SBA-15 materials are widely utilized as heterogeneous catalysts for several organic transformations, − only a few transition-metal-grafted functionalized SBA-15 materials are reported for colorimetric − and electrochemical sensing of toxic pollutants. − The first-row transition-metal immobilization over the surface of SBA-15 is generally achieved through post-synthetic wet impregnation or organic functionalization. These post-synthetic modifications often lead to reduced surface area and pore blockage.…”