A One‐Pot Approach to Multi‐Substituted Fused Aziridines: Formal Intermolecular [2+1] Cycloaddition Reaction between Saccharin‐Derived Cyclic Ketimines and Sulfur Ylides

Abstract

Herein a concise and efficient method for the synthesis of aziridines has been developed. The reaction proceeds through a formal intermolecular [2+1] cycloaddition reaction of saccharin‐derived cyclic ketimines with sulfur ylides. This methodology features high atom‐economy, broad substrate scope and an operationally simple procedure, affording the aziridines with excellent yields and diastereoselectivity (>20 : 1 dr). In the presence of base, the aziridine products could be readily converted to benzothiazines by an unusual rearrangement reaction.

Base mediated aza-[2 + 1] annulation and regioselective aziridine ring-opening cascade: mild synthesis of functionalized β-amino ketones from cyclic N-sulfonyl aldimines and α-carbonyl sulfonium salts

“…The methylated ketimine provided 3o only in 12% yield, and the phenyl group substituted ketimine did not afford the desired bicyclic aziridine probably due to the steric effect (structure not shown). Notably, the saccharin-derived imine substrate 3p, which has proven to be suitable reactant in various annulations, 24 did not give the expected product under our conditions. We then investigated the scope of the α -carbonyl sulfonium salts.…”

“…Coincidently, while our research was underway, Lin disclosed a method toward fused aziridines via saccharin-derived cyclic ketimines and sulfur ylides under reflux conditions. 24 Herein we describe a cascade [2 + 1] annulation/hydrogen-mediated reductive ring-opening reaction between sulfamate-derived cyclic aldimines and α-carbonyl sulfonium salts to access β -AKs derivatives under mild conditions.…”