In the past several years, ?2-dearomatization has been used to modify arenes and produce novel organic compounds. The {TpW(NO)(PMe3)} fragment has proven to be a viable synthetic tool as it is scalable, non-toxic, and cost-effective; however there has been limited success in resolving enantiomerically enriched forms of this metal center. A new methodology for resolution of the racemic dearomatizing agent {TpW(NO)(PMe3)} is currently being developed. In this approach, 1,3-dimethoxybenzene is bound to {TpW(NO)(PMe3)} and protonated via chiral acid, producing two diastereomeric salts. Accordingly, separation of the diastereomers via crystallization, precipitation, and chromatography is being tested. Should separation be achieved, the two diastereomers may be deprotonated and exchanged with other aromatic ligands to form enantio-enriched ?2-species. These systems, which include dearomatized arenes, may be used to facilitate electrophilic addition and cycloaddition reactions on the ring. Finally, the enriched organic product may be removed from the metal via oxidation.Example chiral acids that have demonstrated clean protonation of the TpW(NO)(PMe3)(5,6-?2-1,3-dimethoxybenzene) complex include (S)-camphor sulfonic acid, L-tartaric acid, L-dibenzoyl tartaric acid, and L-di-p-toluoyl tartaric acid. In some cases, the resulting diastereomers may be distinguished from each other in a 1H-NMR spectrum, with near baseline splitting occurring for certain Tp and ring protons. Integration of these �split� peaks provides a measurement of the enantiomeric excess of the mixture. Evidently, this spectroscopic technique proves to be a facile alternative to other methods, such as chiral HPLC, when determining the degree of resolution. With these techniques and spectroscopic methods in hand, unique enantio-enriched products derived from the {TpW(NO)(PMe3)} dearomatizing system may soon be obtained.

Enantio-enrichment of {TpW(NO)(PMe<sub>?3</sub>?)} dearomatizing agent

247th National Meeting (2014)

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Enantio-enrichment of {TpW(NO)(PMe?3?)} dearomatizing agent

Enantio-enrichment of {TpW(NO)(PMe_?3?)} dearomatizing agent