Proton sponges deprotonation

Treatment of either the pyrrole (20) or 1-methylpyrrole (21) complex with methylacetonitrilium triflate gives the iminium-substituted 1//-pyrrole complexes 41 and 42, respectively (Figure 10).llb,12b These complexes are surprisingly resistant to deprotonation with Proton Sponge ... 

It was already mentioned (Section III.A.2) that 4,5-dihydroxy-l,8-bis(dimethylamino) naphthalene actually exists in the form of the internal salt 11139. Somewhat similar is the situation with 2,7-dihydroxynaphthalene 140, also behaving in solution as a betaine165. The latter, on treatment with acids, gives the cation 140-H+, while the action of alkali results in protonated dianion 141 (Scheme 15). All attempts to deprotonate 141 (even with the KOH-DMSO system at 100 °C or with LiH-DMSO) failed. This implies that the basicity of still unisolated dianion 142 lies in the limit of pKa = 25-26 (H2O scale). Thus, dianion 142 can be presently considered as the strongest base among all proton sponge and aniline derivatives. 

Until recently, there had been no reports on the application of 2,7-disubstituted proton sponges like 44 and 65 in organic synthesis. Their advantage in comparison with compound 1 is their increased basicity coupled with their extremely low C-nucleophilicity. Lately, the 2,7-dimethoxy compound 44 was used for deprotonation of salts of other proton sponges, in particular of 88 and 89 (Section n.C.2)67. In another example, when the proton sponge 1 participated in the azo-coupling reaction, the addition of base 44 increased the degree of interaction (equation 30)56. The yield of the azo compound 269 was nearly quantitative, and the base 44 could be easily recovered. 

Pd(alkenyl)(N03)L2] either directly via [PdH(alkyne)L2] or by protonation of [Pd(alkyne)L2]. Zero-valent Pt complexes are obtained in the corresponding reaction with Pt and these may be protonated to give Pt alkenyl complexes. However, evidence that the H atom remains bound to Pd throughout until it is finally transferred to the alkyne came from the observed formation of the alkenyl compound even in the presence of proton sponge . In other cases deprotonation to give Pt followed by protonation is proposed. ... 

The wide reaction scope was facilitated by an extensive investigation into the in situ synthesis of monosubstituted ketenes. A shuttle deprotonation strategy was identified, by which a thermodynamically strong but kinetically slow base such as proton sponge is used as a proton sink, in combination with a substoichiometric kinetically fast tertiary amine (Figure 3.1). Under these conditions the zwitterionic ammonium enolate may be formed via two distinct pathways in... 

Figure 14.17 labeled systems exhibiting strong intramolecular NHN hydrogen bonds. 28 deprotonated mono-anion of 6-nitro-2,3-dipyrrol-2-ylquinoxaline [59]. 29 protonated mono-cation of 1,6-dimethyl-1,6-diazacyclodecane [59] and 30 of 1,8-bis(dimethylamino)-naphthalene (OMAN, proton sponge) [60]. For comparison, the neutral molecules W,W -diphenyl-6-aminopentafulvene-1-aldimine (1, see... 

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