Alkenyl- and aryl[2-(hydroxymethyl)phenyl]dimethylsilanes: Tetraorganosilanes for the practical cross-coupling reaction

Abstract

Readily accessible and highly stable alkenyl- and aryl[2-(hydroxymethyl)phenyl]dimethylsilanes cross-couple with various aryl and alkenyl halides under mild reaction conditions employing K2CO3 as a base at 35-80 °C. The reaction tolerates a diverse range of functional groups including silyl protections. The silicon residue, cyclic silyl ether, is readily recovered and reused on a gram-scale synthesis. Intramolecular coordination of a proximal hydroxyl group is considered to efficiently form pentacoordinated silicates having a transferable group at an axial position.

Cross‐Coupling Reactions of Organosilicon Compounds in the Stereocontrolled Synthesis of Retinoids

“…Also, silanols 8 b and 8' b were obtained indirectly from siloxanes 8 a and 8' a (CH 3 CN, 1.0 m HOAc/NaOAc buffer, pH 5) [29] in 89 and 85 % overall yield, respectively, for the one-pot silylation-hydrolysis procedure. Similarly, [2-(hydroxymethyl)phenyl]silanes 8 l and 8' l were prepared from 8 k and 8' k by deprotection under basic conditions (K 2 CO 3 , H 2 O/CH 3 OH) [23] in 57 and 48 % combined yield for the two steps.…”

“…www.chemeurj.org "reusable" [23] [2-(hydroxylmethyl)phenyl]silane l). For regioand stereoselective preparation of these metallic intermediates, four well-established protocols were examined: transition-metal-catalysed hydrosilylation of alkynes (method A), palladium-catalysed silylation or metal-halogen exchange/ carbanion silylation of vinyl halides (methods B and C, respectively) and stereoselective reduction of alkynylsilanes (method D).…”

“…[48] In this work, fluoride-free coupling of iodide 6 to silanol Table 4). g Me 2 PhSi ---- 21 h We also attempted non-fluoride coupling of [2-(hydroxylmethyl)phenyl]silanes, Hiyama, Nakao and co-workers [23] having reported that intramolecular coordination of the proximal hydroxyl group allows cross-coupling under conditions significantly milder than the standard, and that the metal residue (a cyclic silyl ether) can readily be recovered and reused. In this work, after attempts to couple 8 l with iodide 6 by using various bases (K 2 CO 3 (Table 4).…”

“…Surprisingly, however, failure met all attempts to obtain derivatives 8 d-l and 8' d-l by trapping the same vinyl anions with other commercially available chlorosilanes (benzyldimethylchlorosilane, diisopropylchlorosilane, allyldimethylchlorosilane, aryl-and heteroaryldimethylchlorosilanes) or with 1,1-dimethyl-2-oxa-1-silaindan. [23] Moreover, it was impossible to obtain any of the (1Z,3E)-dienylsilanes 9 by applying this method to precursor iodide 12. In all of these unfruitful attempts, the main reaction product after workup was the terminal alkene 13 (Table 2), the anions generated having been unable to trap the silicon electrophiles.…”

Palladium‐Catalyzed Domino Heck/Silylation Reaction for the Synthesis of (2‐Oxoindolin‐3‐yl)methylsilanes via Trapping of the σ‐Alkylpalladium Intermediates with Disilanes

“…Organosilanes, as a class of important organic compounds with unique chemical, physical, and biological properties, are widely applied to synthetic organic chemistry, [1] material science [2] and medicinal chemistry. [3] As a result, many efficient methods have been developed for the synthesis of organosilane compounds.…”