Reactions of Hydroxy Carboxylic Acid Amides and Their O-Trimethylsilyl Derivatives with Chloro(chloromethyl)- dimethylsilane. Synthesis of 1-Oxa-4-aza-2-sila- and 1-Oxa-4-aza-2,6-disilacyclohexanes* Yu. I. Baukov, A. G. Shipov, E. P. Kramarova, E. A. Mamaeva, O. A. Zamyshlyaeva, N. A. Anisimova, and Vad. V. Negrebetskii Russian State Medical University, Moscow, Russia Received June 17, 1996 Abstract - A general strategy has been developed for the synthesis of 1-oxa-4-aza-2-silacyclohexanes, 1-oxa- 4-aza-2-silacyclohexan-5-ones, and 4-acyl-1-oxa-4-aza-2-silacyclohexanes from carboxylic acid amides con- taining a hydroxy group in the acid and/or amide moiety via two routes. The first of these includes trans- formation of N-monosubstituted carboxamides into corresponding O-trimethylsilyl derivatives which react with chloro(chloromethyl)dimethylsilane in the presence of a base to form unstable N-chlorodimethylsilyl- methyl amide derivatives with a five-coordinate silicon atom. Thermal decomposition of the latter during fractionation yields the target silicon-containing heterocycles with an OSiCH2N fragment. The second route consists of direct treatment of N-monosubstituted carboxamides with a mixture of hexamethyldisilazane and chloro(chloromethyl)dimethylsilane, which results in formation of 1-oxa-4-aza-2-silacyclohexan-5-ones and 4-acyl-1-oxa-4-aza-2-silacyclohexanes in high yields, thus excluding preliminary O-silylation of the starting hydroxy amides. One-pot reactions of N-unsubstituted carboxylic acid amides with a hexamethyldisilazane3 chloro(chloromethyl)dimethylsilane mixture, followed by hydrolysis, yield 4-acyl-1-oxa-4-aza-2,6-disila- cyclohexanes.
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