The application of a domino radical bicyclization for the synthesis of compounds containing the 1-azaspiro[4.4]nonane skeleton in 11–67% yields as a mixture of diastereomers is described (trans configuration preference). This process involved formation and capture of alkoxyaminyl radicals. For this purpose, O-benzyl oxime ethers with a brominated or iodinated aromatic ring or a terminal alkynyl group and an alkenyl moiety were employed as starting materials. The bicyclization was initiated by 2,2′-azobisisobutyronitrile or triethylborane and promoted by Bu3SnH. The best results were obtained with O-benzyl oxime ethers containing an alkenyl moiety tethered to electron withdrawing groups or aryl substituents, whereas oxime radical precursor attached to methyl-substituted olefin precluded the capture of alkoxyaminyl radical, giving rise mainly to monocyclized product.

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An alternative microwave-assisted Krapcho-type reaction of α-mono- and α,α-disubstituted β-keto- and α-cyanoesters was efficiently performed on a silica gel bed.

In this research the sequential generation and cyclization of N-alkoxyaminyl radicals to produce 1-azaspiro[4.4]nonane systems was studied. Competition experiments in benzene at 80°C with brominated oxime ethers using Bu3SnH as...