α-deprotonation of a β-shielded acrylamide creates a distorted lithium 1-aminoallen-1-olate

Publication date: Available online 6 May 2019Source: Journal of Organometallic ChemistryAuthor(s): Rudolf Knorr, Barbara Schmidt, Therese von RomanAbstractThe β-shielded acrylamide N,N-diisopropyl-α-(1,1,3,3-tetramethylindan-2-ylidene)acetamide was prepared through ketone addition of an α-lithiated acetamide, followed by H2O elimination. Its α-deprotonation by n-butyllithium occurred readily in THF without any tendency towards addition reactions at C=O or C-β. The resultant single crystals of a dimeric lithio derivative had triple Li–O coordination and a weakly bonding, ion-pair type Li–C(α) relationship. In tert-butyl methyl ether as the solvent, up to seven pairs of diastereotopic nuclei (both 1H and 13C) established a CS-symmetric lithium 1-aminoallen-1-olate structure that is ascribed to either a thermal ground state or a very rapid (on the NMR time scales) oscillation between two chiral ground states that may resemble the solid-state structure.Graphical abstract

Source: Journal of Organometallic Chemistry - May 7, 2019 Category: Chemistry Source Type: research