Alumina Sulfuric Acid as an Efficient and Recyclable Heterogeneous Catalyst for the O-Silylation of Alcohols, Phenols, and Oximes

Abstract

Alumina sulfuric acid as a recyclable catalyst conducts the transformation of various types of alcohol, phenols, and oximes with hexamethyldisilazane (HMDS) to the corresponding O-trimethylsilylated compounds in good to excellent yields under mild and ambient conditions with short reaction times. The method is highly selective for the conversion of primary alcohols in the presence of secondary and tertiary alcohols. Additionally, the catalyst can be easily recovered and reused at least eight times without detectable loss of reactivity.

Keywords:

• Alcohols
• alumina sulfuric acid
• hexamethyldisilazane
• oximes
• phenols
• trimethylsilylation

Acknowledgments

We are thankful to the Sistan and Baluchestan University Research Council for the partial support of this work.

Notes

^a Yields refer to pure isolated trimethylbenzyloxy silane.

^a Yields refer to the pure isolated products. All known products have been reported previously in the literature and were characterized by comparison of IR and NMR spectra with authentic samples. ^{15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34}

^b The yields of eight consecutive catalytic reactions using the recovered catalyst.

^a iodine;

^b lithium perchlorate;

^c cupric sulfate pentahydrate;

^d alumina sulfuric acid; and

^e isolated yield.