Synthesis and Structure of Hypervalent Diacetoxybromobenzene and Aziridination of Olefins with Imino-λ³-bromane Generated in Situ under Metal-Free Conditions

Abstract

Ligand exchange of p-CF(3)C(6)H(4)BrF(2) with acetoxy groups using AcOH and Ac(2)O affords (diacetoxybromo)benzene in a high yield, which undergoes aziridination of alkenes in the presence of TfNH(2) and sulfamate esters in one pot under mild conditions. The aziridination with TfNH(2) proceeds stereospecifically with retention of stereochemistry of olefins at room temperature using limiting amounts of olefins under transition-metal-free conditions. The one-pot aziridination procedure using sulfamate esters can be applied to the intramolecular versions.

Electrochemical Generation of Hypervalent Bromine(III) Compounds

“…The synthesis of Br III reagents is typically accomplished by a ligand exchange reaction between bromine trifluoride (BrF 3 ) and nucleophilic arene derivatives such as arylsilanes and arylstannanes [13] . For example, BrF 3 reacts with phenyl trifluorosilane to form a relatively unstable phenyl‐ λ 3 ‐bromane 1 [14] that is suitable both as reagent and as entry point for the synthesis of other derivatives via ligand exchange (Figure 1, top) [15, 16] …”

“…[13] For example, BrF 3 reacts with phenyl trifluorosilane to form a relatively unstable phenyl-l 3 -bromane 1 [14] that is suitable both as reagent and as entry point for the synthesis of other derivatives via ligand exchange (Figure 1, top). [15,16] Figure 1. New approach to aryl-l 3 -bromanes.…”

Heterocyclic chemistry

“…A transition metal-free approach to aziridine was reported by Ochiai and co-workers (Scheme 2), involving facile prior synthesis of diacetoxy-l 3 -bromane, which participates in aziridination of alkenes in the presence of trifluoromethanesulfonamide (TfNH 2 ). 2 The reaction on cis-cyclooctene is shown, which probably involves the in situ generation of N-triflylimino-l 3 -bromane as an active nitrenoid species.…”

Hypervalent Bromine(III) Compounds: Synthesis, Applications, Prospects

“…They explored the reactivity of this diacetoxybromoarene in alkene aziridination reactions (Scheme 15). 47 The aziridination reaction proceeds with TfNH 2 or sulfamate esters in a highly stereospecific fashion with retention of the stereochemistry in olefins at room temperature by using the olefins as the limiting reagents. Interestingly, (diacetoxybromo)arenes were also used in C-H amination reactions of alkanes in the presence of a suitable sulfonamide source.…”