Nitrosyl chloride addition to cycloalkenyltrimethylsilanes. An unexpected reversal of regiochemistry of addition, and synthesis of β-​aminosilanes

5-​12-​Membered cycloalkenyltrimethylsilanes and trimethyl(2-​norbornenyl)​silane undergo stereo- and regioselective addn. of nitrosyl chloride, affording silylated chloronitrosocycloalkane intermediates, the corresponding diazene dioxide dimers and eventually α-​chlorocycloalkanones via oxime intermediacy. The addn. is syn, with chlorine and nitrosyl group adding to C-​1 and C-​2 resp. The products dimerize to diazene dioxides, whose stability depends on the conformational flexibility of the ring, the less flexible being more stable. The less stable adducts convert to oximes and further to 1,​2-​dichloro-​1-​nitrosocycloalkanes. The adducts can be hydrolyzed to α-​chloroketones and reduced to β-​aminosilanes. Other interesting observations include transposition of keto group in α-​chloroketones and x-​ray crystal structure of the amide deriv. N-​acetyl-​3-​chloro-​3-​(trimethylsilyl)​norbornane-​2-​amine (6f)​, which reveals -​(CO)​-​HN...H-​CH2-​(CO)​- hydrogen contact

ChemInform Abstract: Addition of NOCl to Cyclic Vinylsilanes: An Unexpected Reversal of Regiochemistry.

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