Stereoselective synthesis of -sulfinylamino isocyanides and 2-imidazolines

An efficient asymmetric synthesis of -sulfinylamino isocyanides is reported on the basis of the highly diastereoselective addition of 9-isocyanofluorene to optically pure N-tert-butanesulfinimines. The resulting optically pure isocyanides readily cyclized to give optically pure 2-imidazolines upon removal of the sulfinyl group. Furthermore, the -sulfinylamino isocyanides were used as chiral inputs in Ugi and Passerini multicomponent reactions to generate new types of (pseudo)peptide scaffolds. Optically pure -sulfinylamino isocyanides are synthesized in a highly diastereoselective addition of 9-isocyanofluorene with N-tert-butanesulfinimines. Follow-up chemistry demonstrates that they are excellent precursors for the preparation of optically pure 2-imidazolines. Furthermore, they are applied in Ugi and Passerini multicomponent reactions; TMSOTf = trimethylsilyl trifluoromethanesulfonate, DIPEA = N,N- diisopropylethylamine.