Formation of Triazinium‐Imidothioate Zwitterions and Their Role as Key Intermediates for Novel S_N(ANRORC) Reaction Pathways

Abstract

The formation of highly reactive zwitterionic triaziniumimidothioate intermediates 10 from bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides is reported. These intermediates are the first structures to be isolated from the reaction pathway between bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides 1 and benzylamines 2. The reaction between 1 and 2 has a very complicated hypersurface and can yield unusual bis(1,2,4-triazolo)-1,3,5-triazinium halides 6, [1,2,4]triazolo [1,3,4]thiadiazolo[1,3,5]triazinium halides 7 or highly substituted guanidines 5. The formation of 6 and 7 can be understood in terms of an S N (ANRORC) process. As could be demonstrated for the tricyclic cations 6, these compounds, together with 7,

Synthesis of Unusually Substituted Ureas Starting from Bis(1,3,4‐thiadiazolo)‐1,3,5‐triazinium Halides via Oxo‐imidothioate Zwitterions

“…In analogy to the results of the mechanistic investigations of Wermann et al [3,7,16] and Lill et al [8] with nitrogen nucleophiles, the hydroxide ion is the nucleophilic reagent in the described reaction. Owing to the highly basic properties of guanidine, the acid-base equilibrium is shifted to the side of the non-nucleophilic guanidinium hydrohalide.…”

“…[8] However, not only amines could serve as nucleophiles but also water or the hydroxide ion. The previous investigations of Wermann et al [3,7] with potassium hydroxide/potassium tert-butoxide prompted us to extend our investigations to the reaction between SNS and the hydroxide ion. This led to novel heterocyclic-substituted ureas 2.…”

“…[1,2] A subsequent period of extensive research finally led to novel [1,2,4]triazolo [1,3,4]thiadiazolo [1,3,5]triazinium (NNS) and bis(1,2,4-triazolo)-1,3,5-triazinium halides (NNN) (Figure 1). [3] By reaction with primary and secondary amines these so-called 5/6/5 cationic heterocyclic systems (SNS) can be converted into a wide variety of highly substituted guanidines (G) and bis(azolyl)alkanes (A1 and A2) (Figure 2). [1,[3][4][5][6][7] Figure 2.…”

“…[3] By reaction with primary and secondary amines these so-called 5/6/5 cationic heterocyclic systems (SNS) can be converted into a wide variety of highly substituted guanidines (G) and bis(azolyl)alkanes (A1 and A2) (Figure 2). [1,[3][4][5][6][7] Figure 2. Heterocyclic compounds resulting from the reactions of SNS cations with primary and secondary amines.…”

“…[7] In the course of this fast multistep reaction cascade a highly reactive betainic triazinium imidothioate is formed, which is the key intermediate for the successive reaction. [3,7] The forma-tion of this betainic intermediate is controlled by the influence of negative hyperconjugation [n N(ex.) /σ* C(4a)-S(5) interaction].…”