Solvent-free synthesis of N-sulfonyl imines using WCl6 as a novel, highly efficient and reusable catalyst

Abstract

WCl 6 was used as a novel, efficient and reusable catalyst for the preparation of N-sulfonyl imines via the condensation of sulfonamides with aldehydes as well as isatin under solvent-free conditions. The turn-over frequency (TOF) value of the catalyst is several times higher than the previously reported catalysts. Clean reaction, simple purification, short reaction time and high yield are some other advantages of this work.

Homo- and Hetero-Oligonuclear Complexes of Platinum Group Metals (PGM) Coordinated by Imine Schiff Base Ligands

“…Water is regarded as a disturbing factor inhibiting the progress of the chemical reaction, which can be eliminated by molecular sieves [21], or dehydrating agents acting as catalysts such as phosphorous(V) oxide supported on silica [22], magnesium perchlorate [23], titanium(IV) chloride [24], aluminum chloride [25] and hydrobromic acid [26]. Apart from conventional methods, there are also more sophisticated ones, including green chemistry methods with synthesis performed in water suspension medium [27] or under solvent-free conditions supported by using the microwave irradiation [28] and montmorillonite K 10 clay [29] or tungsten(VI) chloride as [30] catalyst, or on alumina surface [31]. Rao et al reported an eco-friendly synthesis method in aqueous medium [32].…”

Direct Synthesis of Enolizable N‐Sulfonyl Ketimines Under Microwave Irradiation

“…There are a myriad of methods reported for the synthesis of N-sulfonyl aldimines by (Lewis) acid-catalyzed reactions of aldehydes with sulfonamides (Scheme 1, a). [15] These methodologies, however, are generally not efficient when applied to enolizable ketimines. [16] The lower electrophilicity of the ketone compared to the aldehyde, together with the relatively low nucleophilic power of sulfonamide, make this transformation difficult (Scheme 1, b).…”

Eco-friendly and efficient catalyst-free synthesis of N-sulfonylimines from sulfonamides and aldehydes: crucial role of Al2O3 as a reusable dehydrating agent

“…So far, with the increasing demand for N -sulfonylimines, numerous methods to prepare these compounds have been reported. Most of them involve the direct condensation of sulfonamides with aldehydes and are mediated by: (i) strong Lewis acid catalysts, including FeCl 3 , 12 WCl 6 , 13 ZnCl 2 /SiO 2 , 14 TiCl 4 /Et 3 N, 15 and AlCl 3 , 16 (ii) Brønsted acid catalysts, such as Amberlyst 15/molecular sieves, 17 HY9 zeolite, 18 and sulfamic acid (NH 2 SO 3 H), 19 (iii) organocatalysts, such as pyrrolidine/molecular sieves, 20 and Ar 3 CCl, 21 and (iv) activating reagents, i.e. Si(OEt) 4 , 22 TFAA, 23 Silphox [POCl 3− n (SiO 2 ) n ], 24 and silica chloride (SiO 2 –Cl).…”

“…These stereochemical results are in line with the ones obtained in other procedures described in the literature. 12–29 Interestingly, when a carboxylic amide was used instead of a sulfonyl amide, the corresponding acyl imine was not formed. 34…”

“…These stereochemical results are in line with the ones obtained in other procedures described in the literature. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Interestingly, when a carboxylic amide was used instead of a sulfonyl amide, the corresponding acyl imine was not formed. 34 The catalyst-free approach for the synthesis of N-sulfonylimines was successfully demonstrated.…”