Halogen interchange during complex formation between N-halosuccinimides and quaternary ammonium halides

Abstract

N-Halosuccinimides and quaternary ammonium halides form both 1:1 and 2:1 complexes. Where two different halogen atoms are involved, the complex, in every case studied, has the more electronegative halogen atom associated with the quaternary ammonium ion and the less electronegative halogen atom bonded to the imide nitrogen. Where necessary a halogen interchange reaction occurs to satisfy this requirement. A mechanism for this halogen interchange reaction is proposed.

Enantioselective Haloetherification by Asymmetric Opening of meso-Halonium Ions

“…Although the role of the sodium cation is currently unclear, the similar selectivities of the sodium and the lithium salts in the catalytic reactions suggest that 3·Na is not primarily acting as a Lewis acid in these reactions . Instead of acting as a (Lewis) acid the phosphate anion might initially act as Lewis base toward the halogenating agent forming a phosphate NIPyr complex and thereby activating the NIPyr via Lewis base activation . Iodination of the double bond to the iodonium ion is then quickly followed by an asymmetric opening controlled by the chiral counteranion.…”

Highly ortho‐Selective Chlorination of Anilines Using a Secondary Ammonium Salt Organocatalyst

“…The chloride anion in B could then deprotonate the NsNH in 2 to give the basic NsN nitrogen center, which could trigger the electrophilic aromatic chlorination reaction through the proposed mechanistic pathway B → C → D , and give the product 3 together with the regeneration of 1 g . Although the reaction between 1 and DCDMH might generate molecular chlorine, the poor performance of the Mioskowski reagent in the reaction (Scheme b) suggests that molecular chlorine might not play a crucial role in the ortho ‐chlorination of 2 . The regioselectivity in the electrophilic chlorination of 4 b and the low reactivity of substrate 2 j could be explained by the lack of N−H in the substrates (Scheme c,d).…”

Highly ortho‐Selective Chlorination of Anilines Using a Secondary Ammonium Salt Organocatalyst

“…However,this possibility was ruled out since no reaction was observed when reacting E (prepared according to the literature method) [17] with 2a (Scheme 5b). Although the reaction between 1 and DCDMH might generate molecular chlorine, [20] the poor performance of the Mioskowski reagent in the reaction (Scheme 4b)s uggests that molecular chlorine might not play ac rucial role in the ortho-chlorination of 2.T he regioselectivity in the electrophilic chlorination of 4b and the low reactivity of substrate 2j could be explained by the lack of N À Hi nt he substrates (Scheme 4c,d). [18] Thep oor regioselectivity when using 1h could be rationalized since there is no N-H in 1h and the formation of B becomes impossible (Scheme 4a).…”

“…[19] Thechloride anion in B could then deprotonate the NsNH in 2 to give the basic NsN nitrogen center, which could trigger the electrophilic aromatic chlorination reaction through the proposed mechanistic pathway B!C!D,a nd give the product 3 together with the regeneration of 1g. Although the reaction between 1 and DCDMH might generate molecular chlorine, [20] the poor performance of the Mioskowski reagent in the reaction (Scheme 4b)s uggests that molecular chlorine might not play ac rucial role in the ortho-chlorination of 2.T he regioselectivity in the electrophilic chlorination of 4b and the low reactivity of substrate 2j could be explained by the lack of N À Hi nt he substrates (Scheme 4c,d). We believe that the mechanistic pathway B!…”