Sterically facilitated meta-lithiation of arenes, containing electron-donating groups

Publication date: Available online 6 December 2019Source: Journal of Organometallic ChemistryAuthor(s): Alexander S. Antonov, Victor G. Bardakov, Valeria V. MulloyarovaAbstractThe influence of the bulky trimethylsilyl substituent on the selectivity of metallation of dimethylaniline, anisole and 1-dimethylaminonaphthalene is studied. The neighboring SiMe3 group forces dimethylamino and methoxy groups to occupy a conformation with an unshared electron pair turned towards silicon atom. This forced conformation prevents NMe2 and OMe groups from providing the DOM-effect, thus facilitating meta-metallation with the use of bulky LiCKOR. While the inverted NMe2 group completely suppresses ortho-metallation, the less bulky and more electron withdrawing OMe group demonstrates more rotation freedom allowing selective ortho-metallation with smaller reagents such as n-BuLi or tert-BuLi.Graphical abstract

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