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

Abstract

Cycloalkenyltrimethylsilanes add nitrosyl chloride stereo- and regio- selectively. The addition is syn, with chlorine and nitrosyl group adding to C-1 and C-2 respectively. The products dimerize to diazene dioxides, whose stability depends on the conformational flexibility of the ring - the less flexible are more stable. The less stable adducts convert to oximes and further to 1,2- dichloro-1-nitrosocycloalkanes. The adducts can be hydrolysed 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 derivative 6f, which reveals -(CO)- HN…H-CH2-(CO)- hydrogen contact.