The 2,4,6-Trimethoxyphenyl Unit as a Unique Protecting Group for Silicon in Synthesis and the Silylation Potential of (2,4,6-Trimethoxyphenyl)silanes

Abstract

A series of triorganyl(2,4,6-trimethoxyphenyl)silanes containing various combinations of acid-labile protecting groups for silicon, including allyl, 2,6-dimethoxyphenyl, mesityl, 4-methoxyphenyl, 1-naphthyl, and phenyl, were synthesized and characterized. These compounds served as reagents in a series of experiments to determine the selectivity of the cleavage of the 2,4,6-trimethoxyphenyl group in the presence of the aforementioned groups using an ethereal hydrogen chloride solution to obtain synthetically useful chlorosilanes. Additionally, the silylation potential of trimethyl-, methyldiphenyl-, and triethyl(2,4,6-trimethoxyphenyl)silane under mild (0−35 °C), acidic conditions with O-, N-, and S-nucleophiles was examined. These silylation reagents exhibit both chemo- and regioselectivity with respect to the tested nucleophiles, are neither moisture nor air sensitive and thus easy to handle, and produce a relatively inert byproduct, 1,3,5-trimethoxybenzene, which is recyclable.