[18156-74-6] · C6H12N2Si · N-(Trimethylsilyl)imidazole · (MW 140.29)
(silylating agent for alcohols and 1,3-dicarbonyl compounds;2 reaction with esters to give imidazolides; preparation of O-trimethylsilyl monothioacetals; aromatization of the A-ring of steroids)
Physical Data: bp 93-94 °C/14 mmHg; fp 5 °C; d 0.956 g cm-3.
Form Supplied in: liquid.
Handling, Storage, and Precautions: flammable. Harmful by inhalation, in contact with skin, and if swallowed. Possible carcinogen. Use in a fume hood. When using, wear protective gear and clothing. Handle and store under N2. Store in a cool dry place.
N-(Trimethylsilyl)imidazole is a powerful silylating agent for alcohols (eq 1).2 1,3-Dicarbonyl compounds, although usually existing mostly in the enol form, are not efficiently silylated by standard methods. N-(Trimethylsilyl)imidazole has proved to be an ideal reagent for this transformation (eq 2).3
N-(Trimethylsilyl)imidazole reacts with phenyl and 2,2,2-trifluoroethyl esters under base catalysis to give acylimidazolides (eq 3).4 These imidazolides show reactivity similar to acyl chlorides and therefore are useful in synthesis.5
N-(Trimethylsilyl)imidazole is used in the preparation of O-trimethylsilyl monothioacetals directly from corresponding carbonyl compounds and thiols (eq 4).6 The basicity of the medium due to the imidazole generated during the reaction effectively prevents dithioacetalation.
Aromatization of the A-ring of steroid systems has been achieved by the use of N-(trimethylsilyl)imidazole (eq 5).7
Janet Wisniewski Grissom & Gamini Gunawardena
University of Utah, Salt Lake City, UT, USA