Abstract
Common wisdom might anticipate that two methyl groups placed on a molecular migration route should act as an impediment. However, the "conducted tour" migration of Li+(THF)(4) across the aryl ring ("pi-route") during the cis/trans stereoinversion of alpha-arylvinyllithiums had been found to occur with practically equal velocities in the presence of either one or two ortho-alkyl substituents. We now report that the omission of both ortho-methyl groups retards the stereoinversion process. In order to arrive at an answer to the title question, we investigate the aggregation equilibria and microsolvation states of ortho, ortho'-unsubstituted alpha-lithiostyrenes by means of approved secondary NMR criteria. Beyond such necessary knowledge about the ground-state properties, we provide kinetic evidence showing that the retarded cis/trans stereoinversion of alpha-lithiostyrene proceeds by the pseudomonomolecular, ionic mechanism with Li+(THF)(4) migration.
Dokumententyp: | Zeitschriftenartikel |
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Fakultät: | Chemie und Pharmazie > Department Chemie |
Themengebiete: | 500 Naturwissenschaften und Mathematik > 540 Chemie |
ISSN: | 0040-4020 |
Sprache: | Englisch |
Dokumenten ID: | 67517 |
Datum der Veröffentlichung auf Open Access LMU: | 19. Jul. 2019, 12:22 |
Letzte Änderungen: | 04. Nov. 2020, 13:49 |