Synthesis and structure of N-(diaminomethylidene)- and N-[bis(cyclohexylamino)methylidene]trifluoromethanesulfonamides

Abstract

N-Trifluoromethylsulfonyl-substituted guanidines CF 3 SO 2 N=C(NHR) 2 (R = H, cyclohexyl) were synthesized in nearly quantitative yield by reactions of N-sulfinyltrifluoromethanesulfonamide CF 3 SO 2 N=S=O with urea and of trifluoromethanesulfonamide with N, N′-dicyclohexylcarbodiimide. N-[Bis(cyclohexylamino)methylidene]trifluoromethanesulfonamide was subjected to protonation with trifluoromethanesulfonic acid and bis(trifluoromethanesulfonyl)imide, and the structure of the resulting salts and initial N-trifluoromethylsulfonylguanidines was studied by NMR and IR spectroscopy and DFT quantum-chemical calculations.

Trifluoromethanesulfonamides and Related Compounds

“…Most recently, we have proposed two new approaches to the synthesis of N-triflylguanidines in practically quantitative yield from the reaction of N-sulfinyltriflamide ureas and by addition of triflamide to carbodiimides. 220,258 For the compound with R = cyclohexyl, an X-ray structure was obtained (Figure 3) 220 that proved the presence of the Hbond with one of the amino groups in accordance with the results of NMR and IR spectroscopy. 258 The 1 H NMR spectrum contains two NH signals in 1:1 ratio: a narrow peak at 6.77 ppm and a broad singlet at 8.82 ppm belonging to the free and the intramolecularly H-bonded amino groups, respectively.…”

“…220,258 For the compound with R = cyclohexyl, an X-ray structure was obtained (Figure 3) 220 that proved the presence of the Hbond with one of the amino groups in accordance with the results of NMR and IR spectroscopy. 258 The 1 H NMR spectrum contains two NH signals in 1:1 ratio: a narrow peak at 6.77 ppm and a broad singlet at 8.82 ppm belonging to the free and the intramolecularly H-bonded amino groups, respectively. Comparison of the IR spectra in the solid state and solutions of different concentrations in different solvents also supports the presence of the intramolecular hydrogen bond (for details, see ref 258).…”

Development of CN Coupling Using Mechanochemistry: Catalytic Coupling of Arylsulfonamides and Carbodiimides

“…Such coupling is not normally observed because of poor sulfonamide nucleophilicity. The unusual exception to this is trifluoromethylsulfonamide (1), which was recently found [16] to react with di(cyclohexyl)carbodiimide (DCC) and diisopropylcarbodiimide (DIC; Scheme 1 b). Normally, N-sulfonylguanidines are obtained from activated sulfonyl or carbodiimide derivatives.…”

“…The inability to reproduce this catalytic coupling in solution provided an opportunity to explore a novel reaction using mechanochemistry only. We first compared it to the recently reported [16] catalyst-free coupling of 1 with DCC and DIC. We readily conducted both of these reactions by neat milling and by LAG ( Table 1).…”

“…previously not achievable in solution or mechanochemically (Table 1). [16] To verify the importance of CuCl in enabling the coupling of aromatic carbodiimides, we explored the reaction of 1 with di(o-tolyl)carbodiimide (DOTC). While the reaction did not take place without CuCl, milling with 5 mol % CuCl gave 73 % conversion into the N-sulfonylguanidine as evidenced by 1…”