文摘
A three-step sequence to prepare polycyclic 2,5-dihydropyrroles from α-silyloxy ketones is presented. A Lewis acid-mediated ring fragmentation of cyclic γ-silyloxy-β-hydroxy-α-diazo esters provided tethered aldehyde ynoate intermediates which, when treated with amino acid silyl esters, underwent intramolecular azomethine ylide 1,3-dipolar cycloadditions. The 2,5-dihydropyrrole products were formed in good to excellent yield as single diastereomers.