Silver(I) Oxide-promoted Chemoselective Cross-coupling Reaction of (Diborylmethyl)trimethylsilane

Abstract

The present paper describes a synergistic effect in the Pd-catalyzed Suzuki–Miyaura cross-coupling reaction. The chemoselective cross-coupling reaction of (diborylmethyl)trimethylsilane and aryl halides proceeded at room temperature when a silver salt and KOH were added. The reaction gave benzylboronate derivatives bearing a trimethylsilyl group at the benzylic position.

Opportune gem‐Silylborylation of Carbonyl Compounds: A Modular and Stereocontrolled Entry to Tetrasubstituted Olefins

“…The synthesis of H−C(Bpin) 2 (SiMe 3 ) ( 1 ) can be efficiently completed on gram scale simply by mixing B 2 pin 2 and 2 equiv of (trimethylsilyl)diazomethane (2 m hexane solution) and heating the mixture at 110 °C for 24 h (87 %, isolated yield, Scheme ) . We tentatively examined the deprotonation of H−C(Bpin) 2 (SiMe 3 ) by adding lithium 2,2,6,6‐tetramethylpiperidine (LiTMP) to a solution of 1 in THF at 0 °C, followed by addition of cyclohexanone and subsequent warming up to room temperature for 2 h. After the work up and purification by chromatography the gem ‐silylboronate product 2 was isolated in 95 % (Table , entry 1).…”

“…[12] We tentatively examinedt he deprotonationo f HÀC(Bpin) 2 (SiMe 3 )b ya dding lithium 2,2,6,6-tetramethylpiperidine (LiTMP) to as olution of 1 in THF at 0 8C, followedby addition of cyclohexanone and subsequentw arming up to room temperature for2h. [12] We tentatively examinedt he deprotonationo f HÀC(Bpin) 2 (SiMe 3 )b ya dding lithium 2,2,6,6-tetramethylpiperidine (LiTMP) to as olution of 1 in THF at 0 8C, followedby addition of cyclohexanone and subsequentw arming up to room temperature for2h.…”

Base-Mediated Borylsilylation/Silylation of Ammonium Salts with Silylborane

“…Among the various silanes, 1,1-silylboronate esters is particularly appealing because this nonsymmetric dimetallic unit would largely increase the diversity and complexity of the products through further transformations. In recent years, transition-metal-catalyzed cross-coupling, hydroborylation, and hydrosilylation toward geminal silylboronates have been well-developed. Transition-metal-free borylsilylation has also been achieved with using diazo compounds .…”

Access to Enantioenriched Benzylic 1,1-Silylboronate Esters by Palladium-Catalyzed Enantiotopic-Group Selective Suzuki–Miyaura Coupling of (Diborylmethyl)silanes with Aryl Iodides

“…On the basis of these seminal precedents, we envisioned palladium-catalyzed enantiotopic-group selective cross-coupling of (diborylmethyl)­silanes with aryl halides might afford chiral benzylic 1,1-silyl boronate esters. In fact, the group of Endo reported the racemic version of cross-coupling of (diborylmethyl)­silanes with aryl bromides in the presence of Pd­[P­( t Bu) 3 ] 2 catalyst, aqueous KOH, and stoichiometric Ag 2 O . However, to the best of our knowledge, the enantioselective variants of these reactions are undeveloped.…”

“…In fact, the group of Endo reported the racemic version of cross-coupling of (diborylmethyl)silanes with aryl bromides in the presence of Pd[P(tBu) 3 ] 2 catalyst, aqueous KOH, and stoichiometric Ag 2 O. 11 However, to the best of our knowledge, the enantioselective variants of these reactions are undeveloped.…”