Isocyanatotrimethylsilane

Me3SiN=C=O

[1118-01-1]  · C4H9NOSi  · Isocyanatotrimethylsilane  · (MW 115.23)

(preparation of primary amides from Grignard reagents;1-3 synthesis of trifluoroacetyl isocyanate;4 synthesis of cyclic imides5)

Alternate Name: trimethylsilyl isocyanate.

Physical Data: colorless oil; bp 90-92 °C; fp -2 °C; d 0.851 g cm-3.

Solubility: sol ethers, o-dichlorobenzene, etc.

Form Supplied in: commercially available.

Preparative Method: from Chlorotrimethylsilane and silver isocyanate.6

Handling, Storage, and Precautions: harmful vapor; irritant; flammable liquid; moisture sensitive; use in a fume hood.

Amidation.

Grignard reagents are carboxamidated by isocyanatotrimethylsilane to afford primary amides, presumably by way of the N-silyl amides (eqs 1 and 2).1-3 The use of dioxane as an additive to the ether or THF solvent eliminates the formation of silylated Grignard products.1 Isocyanatotriphenylsilane reacts similarly with phenyllithium and phenylmagnesium bromide to give benzamide (77-80%).7 Reaction of heterocyclic benzyllithium reagents with isothiocyanatotrimethylsilane affords primary thioamides in moderate yield (eq 2).2 N-Hydroxyurea has been prepared from O-silylhydroxylamine and isocyanatotrimethylsilane.4

Preparation of Acyl Isocyanates.

Isocyanatotrimethylsilane has been used to convert trifluoroacetyl chloride to trifluoroacetyl isocyanate.5 In the reaction with 1-naphthalenecarbonyl chloride, cyclization of the intermediate acyl isocyanate provides the imide through an intramolecular Friedel-Crafts reaction (eq 3).8

Related Reagents.

Benzenesulfonyl Isocyanate; 3-(2-Benzyloxyacetyl)thiazolidine-2-thione; Chlorosulfonyl Isocyanate; Isocyanic Acid; p-Toluenesulfonyl Isocyanate; Trichloroacetyl Isocyanate.


1. Parker, K. A.; Gibbons, E. G. TL 1975, 981.
2. Curran, A. C. W.; Shepherd, R. G. JCS(P1) 1976, 983.
3. For a review on carboxamidation of organometallic reagents, see Screttas, C. G.; Steele, B. R. OPP 1990, 22, 269.
4. Muzovskaya, E. V.; Kozyukov, V. P.; Mironov, V. F.; Kozyukov, V. P. JOU 1989, 59, 349.
5. Kiemstedt, W.; Sundermeyer, W. CB 1982, 115, 919.
6. Forbes, G. S.; Anderson, H. H. JACS 1948, 70, 1222.
7. Gilman, H.; Hofferth, B.; Melvin, H. W. JACS 1950, 72, 3045.
8. Frenzel, R.; Domschke, G.; Mayer, R. JPR 1991, 333, 805.

Kathlyn A. Parker & David Taveras

Brown University, Providence, RI, USA



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