Syntheses of Tetrahydrobenzodiazepines via S N 2‐Type Ring‐Opening of Activated Aziridines with 2‐Bromobenzylamine Followed by Copper‐Powder‐Mediated C−N Bond Formation

A synthetic route to 2,3,4,5‐tetrahydrobenzodiazepines has been devised through an S N 2‐type ring‐opening of N‐activated aziridines with 2‐bromobenzylamine followed by an intramolecular cyclization through Cu‐powder‐mediated C−N bond formation. This operationally simple and extremely stereospecific ring‐opening‐cyclization approach is very efficient for the synthesis of a diverse array of the desired benzodiazepine derivatives in excellent yields of up to 94 % and enantiomeric excess of up to >99 %.