Categories: C=N Bond Formation >
Synthesis of N-sulfonyl imines
Pyrrolidine as an organocatalyst enables a general and efficient biomimetic method for the synthesis of aldimines from aldehydes and compounds bearing an amino group. This nucleophilic catalysis proceeds via iminium activation with outstanding yields in the absence of acids and metals under simple conditions. The method has been applied to the synthesis of N-sulfinyl, N-sulfonyl imines, N-phosphinoyl, N-alkyl, and N-aryl imines.
S. Morales, F. G. Guijarro, J. L. G. Ruano, M. B. Cid, J. Am. Chem. Soc., 2014, 136, 1082-1089.
The reaction of an arylaldehyde and a sulfonylisocyanate in a solvent or in neat form under catalyst- and additive-free conditions gives the desired N-sulfonylimine with the release of carbon dioxide. The method offers unique clean efficiency, convenience, and scalability, although it was reported to fail half a century ago.
D. Huang, X. Wang, X. Wang, W. Chen, X. Wang, Y. Hu, Org. Lett., 2016, 18, 604-607.
Tris(2,2,2-trifluoroethyl)borate [B(OCH2CF3)3] is a mild and general reagent for condensation of amides or amines with carbonyl compounds providing N-Sulfinyl, N-toluenesulfonyl, N-(dimethylamino)sulfamoyl, N-diphenylphosphinoyl, N-(α-methylbenzyl), and N-(4-methoxyphenyl) aldimines at room temperature. The reactions are operationally simple, and the products are obtained without special workup or isolation procedures.
J. T. Reeves, M. D. Visco, M. A. Marsini, N. Grinberg, C. A. Busacca, A. E. Mattson, C. H. Senanayake, Org. Lett., 2015, 17, 2442-2445.
The combination of Fe(III), l-valine, and 4-OH-TEMPO catalyzes an oxidation of alcohols followed by condensation with sulfinamide or sulfonamide in one pot to provide N-sulfinyl- and N-sulfonyl imines under mild conditions in very good yields.
G. Zhang, Y. Xing, S. Xu, C. Ring, S. Shan, Synlett, 2018, 29, 1232-1238.