Cycloaddition of benzoheteroazepine III Reaction of 2,3‐dihydro‐1 H ‐15benzodiazepines with dichlorocarbene and stereo‐structures of products

Reaction of 2, 3‐dihydro‐1 H‐ 1. 5‐benzodiazepines with dichlorocarbene generated in situ using benzyltriethylammonium chloride (TEBA) as a phase transfer catalyst in chloroform‐aqueous sodium hydroxide mixture gave mainly 1,2‐cycloadducts, cis and trans‐1a, 3‐disubstituted‐1, 1‐dichloro‐1a, 2,3,4‐tetrahydro‐1 H ‐azirino[1,2‐ a ][1,5]benzodiazepines (2.3), and formylated 1,2‐cycloadducts, trans ‐1a,3‐disubstituted‐1, 1‐dichloro‐4‐formyl‐1a, 2, 3, 4–1 H ‐azirino[1, 2‐ a ][1, 5]benzodiacepines (4). The stereo‐structures of cycloadducts and the mechanism are also discussed.