Silylation of nitro compounds

Conclusions

• 1. The silylation of dimethyl nitromalonate with N, N′-diphenyl-N-trimethylsilylurea, and also of the Ag salt of dimethyl nitromalonate with trimethylchlorosilane, leads to the trimethylsilyl ester of dicarbomethoxymethanenitronic acid, which is more stable then its alkyl analogs, and which reacts with amines, acids and alcohols by a common scheme to give dimethyl nitromalonate and the corresponding trimethylsilyl derivatives.

• 2. The trimethylsilyl ester of dicarbomethoxymethanenitronic acid enters into the 1, 3-dipolar cycloaddition reaction with styrene and methyl acrylate, forming the corresponding 5-substituted N-trimethylsilyloxy-3, 3-biscarbomethoxyisoxazolidines, in which connection the reaction is structurally and spatially selective, and leads to the stereoisomer with the same mutual orientation of the substituent in the 5 position and the -OSi(CH₃)₃ group.

• 3. The inversion of the nitrogen in the obtained 5-substituted N-trimethylsilyloxy-3, 3-biscarbomethoxyisoxazolidines is hindered below 100°, whereas equilibrium mixtures of the stereoisomers are formed when the compounds are heated at a higher temperature.

• 4. Treatment of the 5-substituted N-trimethylsilyloxy-3, 3-biscarbomethoxyisoxazolidines with CH₃·ONa gives the 5-substituted 3-carbomethoxyisoxazolines, and also methoxytrimethylsilane and the Na salt of monomethyl carbonate.