A Facile and Efficient Trimethylsilylation of Hydroxyl Groups Using Silica-Supported Zinc Chloride and Alumina-Supported Sodium Hydrogensulfate as Recyclable Heterogeneous Catalysts

Abstract

Silica-supported zinc chloride (SiO₂-ZnCl₂) and novel alumina-supported sodium hydrogensulfate (NaHSO₄-Al₂O₃) as recyclable heterogeneous catalysts have been used for the mild trimethylsilylation of hydroxyl groups under ambient conditions. This procedure also allows for the selective protection of primary and secondary alcohols in the presence of tertiary alcohols.

Keywords:

• Heterogeneous catalyst
• NaHSO₄-Al₂O₃
• SiO₂-ZnCl₂ (silzic)
• O-trimethylsilylation

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

Notes

^a Isolated yield and the product gave satisfactory IR and NMR spectra.

^a The pure isolated products were characterized by the comparison of their physical data with those of known compounds. ^{5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24}

^b Isolated yields after five times recovery of the catalyst.

^c The amount of HMDS was chosen (1.5 mmol).

^a Catalyst: SiO₂-ZnCl₂.

^b Catalyst: NaHSO₄-Al₂O₃.