Tandem synthesis of N-methylated tertiary amines via three-component coupling of carbonyl compounds, amines, and methanol

Abstract

An Ir-catalyzed tandem synthesis of various N-methylated tertiary amines from three-components coupling of carbonyl compounds, amines, and methanol following reductive amination/N-methylation is reported for the first time. A wide array...

2-(2-Benzimidazolyl)pyridine Mn(I) Complexes: Synthesis and Exploration of Catalytic Activity toward Synthesis of Pyrimidine and Quinoline

“…To inspect this, Mn1 was reacted with NaOMe (1.5 equiv) in methanol, which led to formation of a new complex (Scheme ). This new species was characterized by 13 C NMR spectroscopy, where a new peak at δ = 172.6 ppm (pyridonate CO) was observed which confirmed the formation of complex Mn1′ . , The FT-IR spectrum of Mn1′ exhibits absorptions at 2007 and 1898 cm –1 , which are attributed to the Mn-bound terminal carbonyls along with absorption at 1638 cm –1 for the pyridonate CO which further confirmed the formation of the lactam form of the ligand …”

“…This new species was characterized by 13 C NMR spectroscopy, where a new peak at δ = 172.6 ppm (pyridonate C�O) was observed which confirmed the formation of complex Mn1′. 39,51 The FT-IR spectrum of Mn1′ exhibits absorptions at 2007 and 1898 cm −1 , which are attributed to the Mn-bound terminal carbonyls along with absorption at 1638 cm −1 for the pyridonate C�O which further confirmed the formation of the lactam form of the ligand. 51 Afterward, the interconversion between the lactim and lactam forms of the ligand in Mn1 and Mn1′ was studied (Scheme 6).…”

“…39,51 The FT-IR spectrum of Mn1′ exhibits absorptions at 2007 and 1898 cm −1 , which are attributed to the Mn-bound terminal carbonyls along with absorption at 1638 cm −1 for the pyridonate C�O which further confirmed the formation of the lactam form of the ligand. 51 Afterward, the interconversion between the lactim and lactam forms of the ligand in Mn1 and Mn1′ was studied (Scheme 6). A solution of Mn1 in CH 3 OH was treated with 1.5 equiv of sodium methoxide which led to formation of Mn1′.…”

Utilization of methanol for condensation interrupted chemoselective transfer hydrogenation of CC, CO, and CN bonds under low catalyst loading

“…In contrast, imines derived from benzylamine derivatives are more susceptible to reductive methylation under these reaction conditions due to the enhanced nucleophilicity of the secondary amine N -centre created after the first hydrogenation. 12 a ,14 Hence, the chemoselective reduction of imines derived from benzylamine derivatives is comparatively more challenging (Scheme 1c). Thus, utilizing methanol, the development of an efficient protocol for the chemoselective transfer hydrogenation of the olefinic bond in α,β-unsaturated ketones and further conversion to alcohols and TH of CN bonds in imines is highly appreciable.…”

“…15 To overcome this challenge either a higher reaction temperature or a longer reaction time or a large amount of base is imperative, which further introduces a probability of methylation by the in situ generated formaldehyde. 12 a ,14,16 Therefore, the development of an efficient TH protocol requires a fine balance among the optimum reaction temperature, reaction time, and amount of base.…”