Categories: C=N Bond Formation >
Synthesis of N-sulfinyl 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.
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.
Use of the heterogeneous catalyst amberlist-15 A enables an efficient synthesis of N-(tert-butylsulfinyl)imines under microwave irradiation. Amberlist-15 is convenient to handle, inexpensive, safe to use and quickly separable from the reaction mixture. This method offers a number of advantages including operational simplicity, high yield of products, and broad substrate scope.
C. Sanaboina, S. Jana, L. Eppakayala, Synlett, 2014, 25, 1006-1008.
Microwave-promoted condensation of carbonyl compounds with (R)-2-methylpropane-2-sulfinamide under solvent-free conditions in the presence of Ti(OEt)4 enables a simple, environmentally friendly synthesis of optically pure N-(tert-butylsulfinyl)imines. Sulfinyl aldimines can be prepared with excellent yields and purities in only 10 min, whereas the reaction time for the preparation of ketimines has been extended to 1 h.
J. F. Collados, E. Toledano, D. Guijarro, M. Yus, J. Org. Chem., 2012, 77, 5744-5750.
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.