Nanoporous TiO₂ containing an ionic liquid bridge as an efficient and reusable catalyst for the synthesis of N,N′-diarylformamidines, benzoxazoles, benzothiazoles and benzimidazoles

Abstract

Nanoporous TiO2 modified with an ionic liquid was used for efficient coupling of amines, 1,2-phenylene diamines, 2-aminophenol and 2-aminothiophenol with orthoesters.

Periodic Mesoporous Organosilica Containing Bridged N‐Sulfonic Acid Groups: Promotion of the Synthesis of N,N’‐Diarylformamidines, Benzoxazoles, Benzothiazoles and Benzimidazoles

“…In order to find the best reaction conditions, the influence of the amounts of the catalyst, temperature, solvent and also the amount of triethyl orthoformate was investigated on it and the obtained results were arranged in Table 2. Based on this data, the optimized amount of triethyl orthoformate obtained 1.5 mmol and lower and higher [55] 2 CH(OMe) 3 5 94 168-170 170-171 [55] 3 CH 3 CH(OEt) 3 8 90 170-172 172-174 [53] 4 CH(OEt) 3 15 91 201-202 201-202 [54] 5 CH(OMe) 3 25 90 201-202 201-202 [54] 6 CH 3 CH(OEt) 3 36 89 222-224 227-228 [54] 7 CH(OEt) 3 10 90 111-113 112-114 [53] 8 CH 3 CH(OEt) 3 17 90 198-200 198-200 [53] 9 CH(OEt) 3 4 95 Oil Oil [55] 10 CH(OMe) 3 5 93 Oil Oil [55] 11 CH 3 CH(OEt) 3 5 92 Oil Oil [55] 12 CH(OEt) 3 5 91 Oil Oil [55] 13 CH(OMe) 3 8 92 Oil Oil [55] 14 CH 3 CH(OEt) 3 5 92 Oil Oil [55] [a] Isolated yields. [a] The used catalyst in this procedure was AM-PMO.…”

“…Low-angle powder X-ray diffraction (XRD) of SA-PMO is shown in Figure 2. The synthesized nano reagent exhibits a single intense peak at 2θ near 1°and another reflection peak at 2θ = 1.76°which are indexed to the (100) and (110) diffractions, [55] 2 CH(OEt) 3 3 96 180-182 182-183.5 [50] 3 CH(OEt) 3 4 94 114-116 114-116 [50] 4 CH(OEt) 3 5 90 186-187 186-187 [52] 5 CH(OEt) 3 10 90 139-141 141-143 [ 55] 6 CH(OEt) 3 8 91 125-127 126-128 [52] 7 CH(OEt) 3 12 90 113-115 113-115 [50] 8 CH(OEt) 3 10 90 100-102 108-110 [50] 9 CH(OEt) 3 3 93 238-239 239-240 [56] 10 CH(OEt) 3 25 93 133-135 133-135 [55] 11 CH(OEt) 3 20 90 195-198 195-198 [55] [a] Isolated yields.…”

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

“…The design of an efficient apparatus with the ability to use molecular sieves to trap methanol, short reaction times, easy purication and isolation of the compounds, and excellent conversion and yields are some advantages of this strategy. 123 À as an effective and eco-friendly catalyst through the modication of nanoporous TiO 2 with bis-3-(trimethoxysilylpropyl)-ammonium hydrogen sulfate and then its catalytic activity was investigated for the generation of N,N 0diarylformamidines (80) 127,128 via the N-formylation reaction of anilines (79) with TEOF (5) under solvent-free conditions at 60 C in very short reaction times (3-40 min) in high to excellent yields (83-100%) (Scheme 20). In this research, the formation of the unsymmetrical diarylformamidines or aliphatic formamidines was unsuccessful.…”

Introduction of Two New Brønsted Acidic Ionic Liquids for the Formamide and Formamidine Derivatization of Amines

“…In recent years, preparation and use of different types of catalysts in organic transformations became an important part of our ongoing research program. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] In continuation of these studies and in order to overcome the previously mentioned restrictions on the synthesis of formamides and N, N'-diaryl formamidines, we motivated to report new and straightforward one-pot procedures to obtain these compounds using [DABCO] (HSO 3 ) 2 (Cl) 2 and [DABCO](HSO 3 ) 2 (HSO 4 ) 2 as newly reported efficient ionic liquid catalysts. [31,32] First of all, to optimize the amounts of the catalysts, solvent and temperature, the reaction of 4-chloroaniline (1 mmol), and formic acid (1 mmol) was selected as the model for the preparation of formamides and studied in the presence of different amounts of [ formamidines from the condensation of amines and triethyl orthoformate.…”

“…Although a variety of catalysts have been reported for the synthesis of formamidines and N, N'-diaryl formamidines, some of them suffer from disadvantages such as low yields, long reaction times, non-reusability of the catalyst and etc. Because of using toxic, metal-containing catalysts or expensive, heterogeneous ones [27][28][29][30] cause to utilize non-toxic, cost-saving ILs be more important. So, introduction of more effective methods and catalysts for the synthesis of these compounds is still of great importance.…”