Combinatorial Approach to the Catalytic Hydrosilylation of Styrene Derivatives: Catalyst Systems Composed of Organoiron(0) or (II) Precursors and Isocyanides

(COT)2Fe and the open
ferrocenes (MPDE)2Fe
(MPDE = η5-3-methylpentadienyl) and (DMPDE)2Fe (DMPDE = η5-2,4-dimethylpentadienyl) were found
to function as catalyst precursors for the hydrosilylation of alkenes
in the presence of auxiliary ligands. Screening trials determined
that the optimal catalyst system was composed of (COT)2Fe and adamantyl isocyanide, allowing the selective hydrosilylation
of styrene derivatives with trisubstituted hydrosiloxanes and a polydimethylsiloxane
bearing Me2SiH moieties as the end groups. Under the appropriate
conditions, the dehydrogenative silylation side reaction was completely
suppressed, and the reaction TON exceeded 5000.