Metal-Free Ammonium Iodide Catalyzed Oxidative Dehydrocoupling of Silanes with Alcohols

Abstract

An ammonium iodide catalyzed direct oxidative coupling of silanes with alcohols to give various alkoxysilane derivatives was discovered. tert-Butyl hydroperoxide proved to be an efficient oxidant for this transformation. Attractive features of this protocol include its transition-metal-free nature and the mild reaction conditions.

Keywords

silylation - ammonium iodide - silanes - alcohols - coupling - metal-free catalysis

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• 17 NH₄I-Catalyzed Oxidative Dehydrocoupling of Silanes with Alcohols: General Procedure 70% aq TBHP (4.0 mmol) was added dropwise over 10 min to a solution of the appropriate silane (1.0 mmol) and NH₄I (0.20 mmol) in the appropriate alcohol (1 mL), and the mixture was stirred at r.t. until the reaction was complete (TLC). The reaction was then quenched with sat. aq Na₂S₂O₃, and the mixture was washed with brine, extracted with EtOAc, dried (Na₂SO₄), and concentrated under vacuum. The crude product was purified by column chromatography (silica gel, PE). Ethoxy(triphenyl)silane (3aa) Colorless liquid; yield: 280 mg (92%). ¹H NMR (300 MHz, CDCl₃): δ = 7.66 (d, J = 6.4 Hz, 6 H), 7.42 (dt, J = 13.5, 6.6 Hz, 9 H), 3.90 (q, J = 7.0 Hz, 2 H), 1.26 (t, J = 6.9 Hz, 3 H). ¹³C NMR (75 MHz, CDCl₃): δ = 135.49, 134.55, 130.06, 127.95, 59.85, 18.49. HRMS (TOF, EI⁺): m/z calcd for C₂₀H₂₀OSi: 304.1283; found: 304.1285.