Abstract:The stability vs. reactivity of electrophilic 3‐(triphenylphosphonio)‐cyclopropenium salts towards a neutral nucleophile, such as triphenylphosphane, is reported. Depending on the nature of cyclopropenyl substituents (R), the three‐membered cyclic structure is preserved (R = Ph) or evolves by ring opening to the isomeric linear allene (R = Mes). The respective formation of 1,3‐bis(triphenylphosphonio)‐2,3‐diphenylcyclopropene and 3,3‐bis(triphenylphosphonio)‐1,1‐dimesitylallene products is rationalized on the … Show more
“…17 The dicationic imidazolium salt (1•H)(OTf)2 was obtained in 98% isolated yield upon reacting 1-mesitylimidazole with the chlorocyclopropenium triflate (2)(OTf) in presence of sodium triflate as chloride scavenger in THF at 60°C (Scheme 1). 18 The addition of a triflate source was shown crucial since no reaction occurred in its absence. 19 The air stable salt (1•H)(OTf)2 available on a gram scale precipitated along the course of the reaction and was isolated simply by filtration and washings in spectroscopic and analytical pure form.…”
Section: The Cationic Nhc 1 + Bearing a N-bounded 23bis(diisopropylamentioning
confidence: 99%
“…Hydrogen atoms, except on C2, have been omitted for clarity. Selected bond lengths (Å) and angles (deg): N2-C4 1.4090(18), C4-C5 1.3581(19), C4-C6 1.360(2), C5-C6 1.4426(19), C5-N3 1.2983(17), C6-N4 1.2965(18), C1-N22-C4-C5 81.15.…”
Inspired by the success of α-cationic phosphines, a new cationic NHC, derived from IMes by the formal replacement of an N-mesityl substituent by a cationic cyclopropenium group, is described.
“…17 The dicationic imidazolium salt (1•H)(OTf)2 was obtained in 98% isolated yield upon reacting 1-mesitylimidazole with the chlorocyclopropenium triflate (2)(OTf) in presence of sodium triflate as chloride scavenger in THF at 60°C (Scheme 1). 18 The addition of a triflate source was shown crucial since no reaction occurred in its absence. 19 The air stable salt (1•H)(OTf)2 available on a gram scale precipitated along the course of the reaction and was isolated simply by filtration and washings in spectroscopic and analytical pure form.…”
Section: The Cationic Nhc 1 + Bearing a N-bounded 23bis(diisopropylamentioning
confidence: 99%
“…Hydrogen atoms, except on C2, have been omitted for clarity. Selected bond lengths (Å) and angles (deg): N2-C4 1.4090(18), C4-C5 1.3581(19), C4-C6 1.360(2), C5-C6 1.4426(19), C5-N3 1.2983(17), C6-N4 1.2965(18), C1-N22-C4-C5 81.15.…”
Inspired by the success of α-cationic phosphines, a new cationic NHC, derived from IMes by the formal replacement of an N-mesityl substituent by a cationic cyclopropenium group, is described.
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