Synthesis of HOMSi Reagents by Pd/Cu-Catalyzed Silylation of Bromoarenes with Disilanes

Abstract

Silylation of aryl bromides with disilanes of type {[2-(PGOCH2)C6H4]Me2Si}2 (PG: protecting group) successfully takes place in the presence of a Pd/Ruphos or Davephos/CuI catalytic system to afford HOMSi reagents containing various functional groups in good yields. BisHOMSi reagents were also prepared directly from the corresponding arylene dibromides.

C(sp2)−Si Bond Functionalization through Intramolecular Activation by Alkoxides

“…Bis‐arylation strategies have also been considered on substrates bearing two (or more) halogenated groups, [71] or two (or more) HOMSi units [67,72] . For example, the double functionalization of one equivalent of bis‐aryl bromide 98 was performed in the presence of two equivalents of arylsilane 99 (Scheme 36, top) to deliver 100 .…”

Recent Progress in the Transition‐Metal‐Catalyzed Activation of Si−Si Bonds To Form C−Si Bonds

“…In 2014, Hiyama and co‐workers reported a method for the Pd/Cu‐catalyzed silylation of aryl bromides with disilanes {[2‐(P G OCH 2 )C 6 H 4 ]Me 2 Si} 2 42 , in which P G refers to a protecting group (Scheme ) . The product is readily deprotected to give aryl‐[2‐(hydroxymethyl)phenyl]dimethylsilanes (Ar‐HOMSi), which are reusable reagents for cross‐coupling to synthesize oligoarenes and polyarenes.…”

“…In 2014, Hiyama and co-workers reported am ethodf or the Pd/Cu-catalyzed silylation of aryl bromides with disilanes {[2-(P G OCH 2 )C 6 H 4 ]Me 2 Si} 2 42,i nw hichP G refers to ap rotecting group (Scheme 11). [18] The product is readily deprotected to give aryl-[2-(hydroxymethyl)phenyl]dimethylsilanes (Ar-HOMSi), which are reusable reagents for cross-couplingt os ynthesize oligoarenes and polyarenes. CuI generates the silyl copper spe-cies in situ with disilanes, which makesC uI crucial for efficiency.T he protecting groups strongly affect the yield: 43 a with a (2-methoxyethoxy)methyl (MOM) group and 43 b with at etrahydropyranyl (THP) group are formed in good yields, but 43 c with a tert-butyldiphenylsilyl (TBDPS) group is formed in 54 % yield owing to steric hindrance.…”

Recent Progress in the Cross-Coupling Reaction Using Triorgano­silyl-Type Reagents

“…We decided to scrutinize the catalytic conditions for the synthesis of Ar-HOMSi and found that a Pd/Cu dual catalytic system was effective for the silylation of aryl bromides with protected HOMSi-type disilanes 4 PG and could be used to prepare various protected aryl-HOMSi reagents 5 (Scheme 3). 30 For example, 4-bromotoluene reacted with THP-protected disilanes 4 THP in the presence of [Pd(allyl)Cl] 2 (2.5 mol%), RuPhos (10 mol%), CuI (10 mol%), K 2 CO 3 (2.2 equiv), H 2 O (4 equiv), and dioxane/NMP co-solvents to give THP-protected tolyl-HOMSi 5aa in 73% yield. The disilane 4 THP was prepared easily by the reaction of dichlorotetramethylsilane with the corresponding aryllithium.…”