Efficient Room‐Temperature O‐Silylation of Alcohols Using a SBA‐15‐Supported Cobalt(II) Nanocatalyst

Abstract

The O-silylation of OH groups of alcohols and phenols with hexamethyldisilazane (HMDS) was achieved in high-to-excellent yields using catalytic quantities of a SBA-15-supported cobalt(II) nanocatalyst (typically 0.5 mol-%) at room temperature and under solvent-free conditions. Furthermore, the heterogeneous catalyst showed an excellent durability and can be conveniently reused by filtration for at least twelve times without any noticeable loss of activity.

Silica‐Supported 1st Row Transition Metal (Nano)Catalysts: Synthetic and Catalytic Insight

“…Microwave irradiation enabled the acetylation of aldehydes within minutes in contrast to room temperature conditions [149] . O ‐Silylation of a wide range of alcohols and phenols was also possible at room temperature with hexamethyldisilazane (HMDS) [150] …”

“…[149] O-Silylation of a wide range of alcohols and phenols was also possible at room temperature with hexamethyldisilazane (HMDS). [150] Sakthivel and Ahmed investigated the hydroformylation reaction of 1-octene under syngas atmosphere for the synthesis of linear and ramified aldehydes. [151] Actually, Co 2 (CO) 8 was anchored to a functionalized SBA-15 containing an organosilane ligand containing imido and alkyne groups.…”

Recent advances in catalytic silylation of hydroxyl‐bearing compounds: A green technique for protection of alcohols using Si–O bond formations

“…In 2012, Rajabi and coworkers reported an alternative novel catalyst useful in the solvent-free O-silylation of a wide range of OH groups of alcohols and phenols using SBA-15 functionalized cobalt (II) nanocatalyst. [123] The Co/SBA-15, as a lewis acid, was used for the O-silylation of OH groups of alcohols and phenols using HMDS with typical benefits of heterogeneous catalyst, namely, easy handling, operational simplicity, higher yield, easy recovery and recyclability (12 times), low loading of catalyst, and with facile filtration workup. In this sense, various hydroxyl-bearing compounds, including aliphatic alcohols, phenols and diols, reacted with HMDS (0.6 mmol) reagent in the presence of Co (II)/SBA-15 (0.005 mmol, 0.017 g) as a highly efficient and recyclable nanocatalyst and produced their corresponding silyl ethers under solvent-free and mild conditions at r.t. in good-to-excellent yields (98%-99% and in one case 92%) and in short reaction times (10-90 min) (Scheme 28).…”

“…In this sense, various hydroxyl-bearing compounds, including aliphatic alcohols, phenols and diols, reacted with HMDS (0.6 mmol) reagent in the presence of Co (II)/SBA-15 (0.005 mmol, 0.017 g) as a highly efficient and recyclable nanocatalyst and produced their corresponding silyl ethers under solvent-free and mild conditions at r.t. in good-to-excellent yields (98%-99% and in one case 92%) and in short reaction times (10-90 min) (Scheme 28). [123] Shaterian and coworkers reported silylation of alcohols, phenols, and naphthols by HMDS in the presence of a recoverable solid heterogeneous phosphorus pentoxide supported on alumina (P 2 O5/Al 2 O 3 ) catalyst. In the presence of a catalytic amount of (P 2 O5/Al 2 O 3 ), trimethylsilylation of a variety of hydroxyl groups, such as benzylic alcohols, primary, secondary, and tertiary alcohols, phenols, and naphthols, by the use of HMDS under solvent-free, mild, and ambient conditions produced their corresponding silyl ethers in moderate-to-excellent yields at r.t bond to produce the reactive silylating agent (I).…”

An Efficient Synthesis of Coumarin Derivatives Using a SBA-15 Supported Cobalt(II) Nanocatalyst

“…In continuation with research efforts from our groups directed towards the design and development of advanced nanocatalytic materials for fine chemicals production [21][22][23], this contribution discloses an efficient, greener and mild catalytic protocol for the synthesis of coumarin derivatives using a previously reported and extensively investigated Co/SBA-15 solid acid nanocatalyst. Excellent yields to coumarins could be obtained using the Co/SBA-15 system under solvent-free conditions.…”