Hydrosilanes are a versatile reagent for organic syntheses, used widely in academia and industry. They are regularly used for the reduction of C=E bonds (where E is C, N, O) and as reagents for halogen/hydride exchange. Deuterium labelling remains an important field in mechanistic studies. Silane deuteration classically relies on stoichiometric quantities of LiAlD<sub>4</sub>. Although there are a handful of catalytic methods for deuterating silanes, these mostly employ expensive precious metals and are limited to tertiary silanes: we sought to address this bottleneck in synthesis.<br/><br/>We recently developed an iron-catalyzed dehydrocoupling (DHC) to access Si-E bonds (where E= N, O, P). Mechanistic studies revealed under an atmosphere of deuterium, deuteration was observed in the dehydrocoupled products, revealing the potential to activate deuterium gas. Modifying the stoichiometry of the DHC reaction opens the opportunity to generate deuterosilanes. Herein, we report an iron-catalyzed deuteration of silanes using deuterium gas. The deuteration of primary, secondary and tertiary silanes is investigated along with other hydride sources. The onward reactivity of the deuterosilanes is explored for facile access to deuterium labelled products by a ‘one-pot, two-step’ process. A combination of synthetic and theoretical investigations reveals a plausible mechanism for the process, based on an iron-hydride intermediate.

Iron-catalyzed deuteration of silanes using deuterium gas

ACS Spring 2022

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