Capture-Collapse Heterocyclization: 1,3-Diazepanes by C-N Reductive Elimination from Rhodacyclopentanones

Rhodacydopentanones derived from carbonylative C-C activation of cyclopropyl ureas can be captured by pendant nucleophiles prior to collapse to 1,3-diazepanes. The choice of N-substituent on the cyclopropane unit controls the oxidation level of the product, such that C4-C5 unsaturated or saturated systems can be accessed selectively.