Synthesis of polycyclic β-lactams. Evolution of tertiary radicals generated by Cp2TiCl from 1,5- and 1,6-epoxynitriles

Radical cyclisation induced by Cp2TiCl of several 1,5- and 1,6-epoxynitriles derived from β-lactams gave 3-oxo-4-methyl-4-hydroxymethylcarbapenams or 4-oxo-5-methylbenzocarbacephems. Apart from these polycyclic β-lactams, the generated alkyl tertiary radicals also evolved to enamides through β-fragmentation and reduction and the tertiary homobenzyl radicals gave a 3,4-trans-6-hydroxymonolactam by hydrogen transfer.