Trimethylsilyl Azide TMSA

Preparative Methods several methods for the synthesis of this azide have been reported. The procedure involving aluminum chloride is not recommended, since an explosive product is formed. Azidotrimethylsilane is now commercially available, and a representative synthetic procedure is as follows. A mixture of sodium azide and chlorotrimethylsilane is refluxed in di-n-butyl ether for 2 days and the azide is safely distilled directly from the reaction vessel. Purer compound (99% content) is obtained by redistillation of the product. Several improved conditions have been reported for the preparation of this azide. In these procedures, trimethylsUyl chloride is reacted with sodium azide either neat or in a high boiling point solvent, such as a mixture of silicone oil and polyethylene glycol. Distillation of the crude product usually provides trimethylsilyl azide (TMSA) in high purity (97.9%) and yield (97%). ... 

Earlier, we observed that diazomethane reacts with MA at 20 C to yield a ring-enlarged lactone 27 due to carbene insertion into the OC—O bond of the anhydride. It has been observed that trimethylsilyl azide (TMSA) instead inserts into the bond between the olefinic carbon and carbonyl grouping. No triazoline derivative was reported. Washburne et utilized this reaction to synthesize oxauracils. They treated MA with TMSA to obtain the silyl derivative 41 which could be converted to oxauracil 42 in a 60-80% overall... 

Table 2.2 Trimethylsilyl azide (TMSA) physical and chemical properties...

Besides the ring-forming reactions already described, trimethylsilyl azide (14) gives an access to a great variety of products. As an important property the excellent stability of 14 must be noted228,229> which makes it more advantageous to employ TMSA (14) instead of other azides. 

An extension of these methods that employs hydrazoic acid as an azide donating agent was developed by Tsuge and co-workers. They used TMSA (146) and allowed it to react with synunetrical M,hf -diphenylcarbodiimide or Nd f -dialkyl carbodiimides 239 in dry benzene at 50-60 °C for 48 hours. The products of these conversions were l-phenyl-5-[N-(trimethylsilyl)-anilino]-... 

Acyl halides react with TMSA to give trimethylsilyl halides and the corresponding isocyanates in a range of 83-98% yields, which are rearranged from the acyl azides via the Curtius degradation (eq 2). However, a reaction of aroyl chlorides with TMSA in the presence of zinc iodide at 0 °C gives the corresponding azides in 85-96% yields (eq 3). ... 

Siloxy Isocyanates. Acyclic anhydrides react with TMSA in a manner similar to acid halides to give equal amounts of trimethylsilyl esters and isocyanates (eq 7). Similarly, cyclic anhydrides react with the azide to give < -trimethylsiloxycarbonyl alk(en)yl isocyanates (eq 8) which are further transformed into l,3-oxazine-2,6-dione derivatives (70-90%). ... 

The easiest synthesis is based on the technically accessible trimethylsilyl chloride, which is converted with sodium azide in a two-phase reaction to yield TMSA ... 

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