Interception of amide ylides with sulfonamides: synthesis of (E)-N-sulfonyl amidines catalyzed by Zn(OTf)₂

Abstract

Through the interception of amide ylides with sulfonamides, we herein report the first general example of an intermolecular condensation reaction between sulfonamides and amides. Beyond formamides, this approach was successfully applied to a variety of lactams and linear amides, giving rise to a broad array of (E)-N-sulfonyl amidines.

Transition metal- and catalyst-free one-pot green method for the synthesis of N-sulfonyl amidines via direct reaction of sulfonyl azides with amines

“…With 2 : 1 ratio of azide to amine, the compound 3a was obtained in 25% yield (entry 12). The reaction afforded 3a in good yield at a reux condition (entries [13][14][15][16]. When the reaction was conducted in the presence of TEMPO (1 eq.…”

“…With secondary amines, the reaction proceeded by the enamine I formation via a known conversion of diethylamine to enamine I (Scheme 4). 14…”

“…In the past years, various methods have been developed for the synthesis of N-sulfonyl amidines. [13][14][15][16][17][18][19][20][21] These include: (a) condensation of amides with sulfonylamides, 13,14 (b) Cucatalyzed three-component coupling reactions of sulfonyl azides, alkynes and secondary amines, 15 (c) Pd-catalyzed carbonylation/coupling of sulfonylazides and substituted amides, 16 and (d) cross-coupling reaction of sulfonyl azides with tertiary amines [17][18][19][20][21] (Scheme 1). Among them, cross-coupling of sulfonyl azides with tertiary amines has attracted much more attention.…”

Photoinduced Cascade Reaction of Tertiary Amines with Sulfonyl Azides: Synthesis of Amidine Derivatives

“…In the past years, great efforts have been focused on developing a new method to prepare amidines. Wan and co‐workers found that the direct condensation of amides and sulfonamides gave amidines in good yields under the condition of NaI/TBHP or Zn(OTf) 2 /EDA (Scheme a) . The coupling of tertiary amines with sulfonamides offered amidines on the basis of the in situ generation of TsNBr 2 (Scheme b) .…”

“…Wan and co-workers found that the direct condensation of amides and sulfonamides gave amidines in good yields under the condition of NaI/TBHP [13] or Zn(OTf) 2 /EDA (Scheme 1a). [14] The coupling of tertiary amines with sulfonamides offered amidines on the basis of the in situ generation of TsNBr 2 (Scheme 1b). [15] Recently, excellent strategies were applied to prepare amidines through the cascade reaction of tertiary amines with sulfonyl azides promoted by CuCl/CCl 4 , [16] electrocatalysis, [17] diethyl azodicarboxylation, [18] and FeCl 3 , [19] and the enamine generated from oxidative dehydrogenation as a key intermediate in these reactions (Scheme 1c).…”