Au/TiO₂catalyzed reductive amination of aldehydes and ketones using formic acid as reductant

Abstract

The combination of commercial easily available Au/TiO2 as catalyst and cost-effective formic acid as reductant was able to render reductive amination of various carbonyl compounds.

One‐pot Reductive Amination of carbonyl Compounds with Nitro Compounds by Transfer Hydrogenation over Co–Nx as catalyst

“…[9] Compared with other methods, reductive aminationh as several advantages such as good availability of the substrates and high atomic efficiency.T he reductivea minationo fc arbonyl compounds with primary amines has been extensively studied for the synthesis of secondary amines. [10][11][12] Primary amines can be simply produced by the hydrogenation of nitro compounds prior to use. Thus, it is attractive to perform ao ne-potr eductive aminationo fc arbonyl compounds with nitro compounds for the synthesis of secondary amines,w hich avoidst he separation and purification of the primary amines in the first step.…”

Development of recyclable gold nanoparticles for routine benchtop catalysis in organic transformations.

“…Terminal aliphatic alkyne also worked well ( Table 5, entry 5). The hydration of internal alkynes was slower than that of terminal alkynes, and a slightly higher catalyst loading (1 mol %) was needed to achieve good yields ( Table 5, entries [6][7][8]. Alkenes and carboxylic acids were well tolerated ( Table 5, entries 9 and 11), but the -OH group in 1-ethynylcyclohexanol (2'-1j) did not survive the hydration condition ( Table 5, entry 10).…”

“…Primary amines (Table 17, entries 1-5), cyclic secondary amines (Table 17, entries [6][7][8] and acyclic secondary amines ( It was also found that when the amine partners were absent, the tandem reduction/formylation product 6-6 could be obtained in one pot. Because deformylation could be achieved selectively in the presence of other ester groups, this O-formylation method may prove beneficial on those reactions that need to protect alcohol groups in a complex synthetic sequence.…”

“…Although addition of bases to the reaction system may stabilize substrates containing acid-sensitive functional groups, more often than not, a base will quench the reactivity of cationic gold catalysts by inhibiting or slowing down multiple stages in the cationic gold catalytic cycle. 7 As mentioned in introduction, the catalytic activity of Au NPs towards electrophilic activation of alkynes could be attributed to its partial oxidation, by oxygen or other oxidants, to higher valence gold species. 38a, 40 We speculated that Au NPs activated by partial oxidation could be more tolerant towards bases.…”

“…Based on the unique alkynophilic ability of gold catalyst, a two-stages gold catalytic cycle has been well accepted (Scheme 1). 7 In stage 1, the cationic gold specieswill activate triple bond and followed by a nucleophilic attack on the gold activated π-complex alkyne A to give a trans-alkenyl gold intermediate B. In stage 2, the resulting vinyl gold complex will react with a proton to furnish the final product through protodeauration, and meanwhile the cationic gold species is regenerated through this Scheme 1.…”