Preparation, characterization and application of succinimidinium hydrogensulfate ([H-Suc]HSO₄) as an efficient ionic liquid catalyst for the N-Boc protection of amines

Abstract

In this work, succinimidinium hydrogensulfate ([H-Suc]HSO 4 ), as a novel Brønsted acidic ionic liquid is prepared and characterized by studying its FT-IR, 1 H NMR, 13 C NMR, mass and SEM. This reagent can be used as an efficient catalyst for the N-Boc protection of amines at room temperature and neat conditions. This new method consistently has the advantages of excellent yields and short reaction times. Further, this ionic liquid can be recovered and reused for several times.

Acidic Ionic Liquids

“…586 succinimidinium hydrogensulfate, as efficient catalysts for the room temperature amine protection reaction under neat conditions. 587 The miscellaneous catalysis applications of BAILs include: the insertion of α-diazoacetate into the N−H bonds of amines, 485 regioselective thiocyanation of aromatic and heteroaromatic compounds at room temperature, 588 and conversion of alcohols to azides. 589 Selective nitration of phenols is another instance where nitration with sodium nitrate could be carried out in the presence of acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate [C 4 C 1 im][HSO 4 ] at room temperature, in good to high yields and short reaction times.…”

“…N-Boc protection of amines is a common synthetic operation. Shirini and co-workers have introduced a new class of BAIL, succinimidinium hydrogensulfate, as efficient catalysts for the room temperature amine protection reaction under neat conditions . The miscellaneous catalysis applications of BAILs include: the insertion of α-diazoacetate into the N–H bonds of amines, regioselective thiocyanation of aromatic and heteroaromatic compounds at room temperature, and conversion of alcohols to azides …”

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 . 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 …”

“…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.…”

The first report on phosphonate-based homopolymers combining both chelating and thermosensitive properties of gadolinium: synthesis and evaluation

“…6-(tert-butoxycarbonylamino)hexylamine was prepared in 70% yield using known procedure. 25 (20 mL) were consecutively added dimethylaminopyridine (DMAP) (4.63 g, 37.89 mmol), diethylphosphonoacetic acid (6.19 g, 31.56 mmol), and dicyclohexylcarbodiimide (DCC) (7.83 g, 37.95 mmol), all dissolved in anhydrous dichloromethane (3 × 10 mL). The mixture was allowed to stir at 25 °C during 24 hours and then cooled to the freezer during the night.…”