The arsonium salt [Ph3As-CH2-OTf]+ OTf- 11a contains a 1,1-biselectrophilic Csp3 center which permits to synthesize a wide range of symmetrical and unsymmetrical geminally bisonio-substituted methane derivatives. With neutral nucleophiles INu under mild condi- tions a series of 1.1-bisonium salts [Ph3As-CH2-Nu]2+ 2OTf- 12-23 is obtained in good yields. Under more stringent conditions the triphenylarsonio function in these salts can also be mobilized as a nucleofuge in a subsequent SN-reaction with a second nucleophile | Nu’, yielding a series of novel unsymmetrical 1,1-bisonium salts [Nu-CH2-Nu’]2+ 2OTf- 24-27. Structures 18, 23 and 26b were confirmed by X-ray analysis. For certain nucleophiles a discrete stepwise substitution of both nucleofuges in 11a cannot be realized and the corresponding symmetrical 1,1-bisonium salts (e.g. 28 and 30-32) are obtained directly. The experimental material can be rationalized on the basis of a simple MO model. The conclusion is that stabilization of a hypervalent SN2 transition state by an equatorial oniosubstituent parallels the stability of the underlying ylids. This is corroborated by model calculations. The geminal bisonium salts reported are potential precursors to mono- and 1,1-bisylids and, in special cases, to functional nucleophilic carbenes.
Sulfonium salts [R2S-CH2-OTf]+ OTf- 1a,b are synthetically versatile 1,1-biselectrophiles featuring the sulfonio- and triflato-substituents as leaving groups of differential nucleofugic power. Reactions with a number of neutral nucleophiles |Nu yield a series of novel sulfoniom ethylated onium salts [R2S-CH2-Nu]2+ 2OTf- 2 - 8 under very mild conditions. Structures of salts 2a, 5a and 6b were confirm ed by X -ray analysis. With certain N -hetarenes exchange of both nucleofuges in la was achieved, yielding the symmetrical 1,1-bisonium salts 9 and 10. With pyridine(derivatives) selective substitution of the sulfoniofunction in 1,1-bisonium systems 2a and 5a was also realized. These reactions represent typical examples of nucleophilic substitutions at geminally bisonio substituted Csp3 centers, which we recently have introduced as a novel variant of Sɴ2 reactivity.
砜盐[R2S-CH2-OTf]+ OTf- 1a,b是一种合成多功能的1,1-双亲电子受体,具有硫烷基和三氟甲烷基取代基作为不同核离散能力的离去基团。与一系列中性亲核试剂|Nu反应,在非常温和的条件下生成一系列新型硫烷基化的烷基化磺酸盐[R2S-CH2-Nu]2+ 2OTf- 2 - 8。盐2a、5a和6b的结构经X射线分析确认。通过对la中某些N-杂环化合物的反应,实现了两个核离散基团的交换,形成对称的1,1-双磺酸盐9和10。对于吡啶(衍生物),也实现了对1,1-双磺酸盐系统2a和5a中硫烷基功能的选择性取代。这些反应代表了我们最近引入的作为Sɴ2反应的一种新变体的烷基化双磺酸Csp3中的亲核取代的典型示例。
A thioether-substituted diaminocyclopropenium (TDAC) cation is developed as a redox shuttle additive for safer high energy density Li-ion batteries.