α‐Cyanation of Aromatic Tertiary Amines using Malononitrile as a Low‐Toxic Cyanide Source under the Catalysis of NiGa Layered Double Oxide

Abstract

NiGa layered double oxide (Ni 3 Ga-LDO) has been found to be an efficient heterogeneous catalyst for the αcyanation of aromatic tertiary amines using malononitrile as a low-toxic cyanide source. Various aniline and aryltetrahydroisoquinoline derivatives were found to be tolerated by the catalytic system, and good to excellent yields for the corresponding products could be obtained. The results indicated that CN À might be produced via a oxidationdecomposition path, and the reaction probably proceeded via a cross-dehydrogenative coupling process. In addition, good stability and recyclability were observed for Ni 3 Ga-LDO catalyst in the reaction. α-Aminonitriles are highly useful and versatile synthetic intermediates for the preparation of α-amino carbonyl compounds, α-amino alcohols, vicinal diamines and alkaloids, which are critical for the construction of a variety of synthetically and biologically important compounds. [1] Classically, the synthesis of α-amino nitriles is always achieved by the Strecker reaction, a three-component condensation of a carbonyl compound, an amine, and cyanide. [2] An alternative route to α-amino nitriles is applying the cross-dehydrogenative-coupling (CDC) reaction, which is advantageous since the imines are generated in situ via C-H bond activation thus precluding their separate synthesis from their respective amines. Actually, the strategy has been extensively studied and various catalytic systems including Cu, [3] Ru, [4] V, [5] Au, [6] I 2 , [7] Mn, [8] Co, [9] Fe, [10] thiourea, [11] and photo-catalyzed conditions, [12] etc. have been developed. However, the cyanide sources for most of these protocols were cyanide salt [4,10a,g-i,12c] or TMSCN, [6,8,12a,b,13] which are quite toxic and user unfriendly. Benzoyl cyanide, [10j] ferricyanide, [10e] potassium thiocyanate, [14] cyanobenziodoxolones, [15] and ethyl cyanoformate, [9,10b,c,f] have also been employed as the cyanic sources, but some of them were prepared from toxic cyanide salt, or quite expensive, or generated metal wastes during the

Highly Dispersed NixGay Catalyst and La2O3 Promoter Supported by LDO Nanosheets for Dry Reforming of Methane: Synergetic Catalysis by Ni, Ga, and La2O3

“…TEM images indicated that Ni x Ga y alloy and La 2 O 3 nanoparticles were well dispersed on the LDO nanosheet without severe aggregation. Accordingly, XRD peaks at around 51.4° attributed to Ni x Ga y alloy could also confirm the production of the alloy catalyst by reduction.…”

Environmentally Benign Synthesis of Quinoline–Spiroquinazolinones by Iron-Catalyzed Dehydrogenative [4 + 2] Cycloaddition of Secondary/Tertiary Anilines and 4-Methylene-quinazolinones

“…Based on these preliminary experimental results and previous literature reports, , a plausible mechanism for this dehydrogenative annulation reaction can be proposed in Scheme . In the presence of Fe 3+ , hydroxy peroxide performs a Fenton-like reaction to generate a hydro-peroxy radical.…”