CO2 on a tightrope

• Verfasst von: Häußermann, Achim [VerfasserIn]
• Verfasst von: Rominger, Frank [VerfasserIn]
• Verfasst von: Straub, Bernd Franz [VerfasserIn]
• Titel: CO2 on a tightrope
• Titelzusatz: stabilization, room-temperature decarboxylation, and sodium-induced carboxylate migration
• Verf.angabe: Achim Häußermann, Frank Rominger, and Bernd F. Straub
• Umfang: 12 S.
• Fussnoten: Gesehen am 24.04.2018 - Im Titel ist die Zahl "2" tiefergestellt
• Jahr Quelle: 2012
• Band/Heft Quelle: 18(2012), 44, S. 14174-14185
• DOI: doi:10.1002/chem.201202298
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1572341270

Abstract

A sterically shielded 3-substituted zwitterionic N,N-dimethylisotryptammonium carboxylate has been synthesized by consecutive chemoselective double alkylation of indole. The carboxylate undergoes a quantitative and unusually facile decarboxylation in dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF) at room temperature. The breaking of a nearly equidistant hydrogen bond by solvent molecules initiates heterolytic CC cleavage. The decarboxylation rate decreases with increasing CO2 partial pressure, proving the competitiveness of protonation and re-carboxylation of the carbanionic intermediate. Corresponding spiro compounds containing silylene and stannylene moieties show high thermal stability. Addition of an excess of methyllithium to the sodium salt triggers a reaction sequence comprising a deprotonation, carboxylate transfer, and nucleophilic trapping of the rearranged carboxylate by another equivalent of methyllithium. Hydrolytic work-up of the geminal diolate leads to an acetyl product. The role of the sodium counterion and the mechanism of the rearrangement have been unraveled by deuteration experiments.