Fig. 1. (a) Methionine sulfoximidation and N–H cross-coupling. Conditions: 1a (0.01 mmol), PhI(OAc)2 (0.025 mmol), and NH2COONH4 (0.2 mmol) in MeOH (1 mL); 1b (0.2 mM), 4-methoxylphenylboronic acid (2 mM), and Cu(OAc)2 (1 mM) in MeOH. (b) Crude HPLC trace and ESI-MS spectrum of oxidation reaction. (c) Crude HPLC trace and ESI-MS spectrum of coupling reaction (with an internal standard). (d) MALDI-MS/MS spectrum of 1b. (e) MALDI-MS/MS spectrum of 1d. (f) Sequence and fragmentation ladder of 1b. (g) Sequence and fragmentation ladder of 1d.
