Asymmetric Hydrosilylation of β-Silyl Styrenes Catalyzed by a Chiral Palladium Complex

Abstract

A palladium complex coordinated with a chiral SIPHOS ligand was evaluated as an efficient catalyst for asymmetric hydrosilylation of β-silyl styrenes with trichlorosilane and 23 1,2-bis­(silyl) chiral compounds were produced. Good to excellent enantioselectivities were observed with 1-aryl-2-silyl ethanols, where the trichlorosilyl groups of the hydrosilylation products were selectively converted into a hydroxyl group in the presence of pre-installed trialkylsilyl groups. Asymmetric hydrosilylation of β-silyl styrenes followed by methylation of the trichlorosilyl group gave stable 1,2-bis­(silyl) chiral compounds 4 with excellent yields. DFT calculations of hydridopalladium B coordinated with a SIPHOS ligand, an intermediate of the hydrosilylation reaction, established the optical structures to be energy minima, and the structural information could well illustrate the enantioselectivity for the hydrosilylation reaction.

Palladium‐Catalyzed Enantioselective Hydrofunctionalization of Alkenes: Recent Advances

“…In 2022, Li and coworkers reported an enantioselective Palladium/SIPHOS( L11 ) complex catalyzed hydrosilylation of β‐silyl styrenes with trichlorosilane, and afforded different 1,2‐chiral bis(silyl) compounds with high yields (Scheme 10). [46] Furthermore, the oxidation of the asymmetric hydrosilylation products yield various β‐hydroxysilanes with good to excellent enantioselectivities (up to 98 % ee).…”

An unusualtrans-hydrosilylation of prochiral 1,1-disubstituted cyclopropenes revealing the different nature of asymmetric palladium and rhodium catalysis

“…This is likely due to low reactivity of internal alkenes for unproductive chelation with transition-metal catalysts, resulting in the need for special ligands to allow acceptable reaction rates and efficiency as well as stereoselective control. A limited number of previous examples of enantioselective transition-metal-catalyzed hydrosilylation of internal alkenes include Pt-catalyzed hydrosilylation of alkenyl boronates with PhMe 2 SiH, 13 Pd-catalyzed Si–C bond-forming transformations of HSiCl 3 or other monohydrosilanes with norbornene, 14 β-silyl styrene, 15 or maleimides, 16 Cu or Co-catalyzed desymmetric hydrosilylation of prochiral disubstituted cyclopropenes, 17 and Cu-catalyzed hydrosilylation of 1,2-dihydroquinolines with Ph 2 SiH 2 . 18 In this context, inspired by previous reports on transition-metal-catalyzed hydrometallation-initiated functionalizations of cyclopropenes (Fig.…”