Iridium‐Catalyzed Asymmetric Transfer Hydrogenation for Facile Access to Optically Active Dihydrodibenzo‐Fused Azepines

Abstract

The asymmetric transfer hydrogenation of various dibenzo‐fused azepines including 5H‐dibenzo[b,e][1,4]diazepines, dibenzo[b,f][1,4]thiazepines and 11H‐dibenzo[b,e]azepines using chiral iridium diamine catalysts and HCO2H/NEt3 as the hydrogen source has been accomplished. A rang of chiral 10,11‐dihydro‐5H‐dibenzo[b,e][1,4]diazepines, 10,11‐dihydrodibenzo[b,f][1,4]thiazepine and 6,11‐dihydro‐5H‐dibenzo[b,e]azepines have been prepared in 82‐94% yields with 82‐99% ee. Diversely substituted substrates are suitable for this transformation, and a number of functional groups are tolerated. The enantiocontrol is achieved via judicious choice of catalyst, additive and hydrogen source. The synthetic potential of this reaction is explored through gram‐scale reactions without loss of reactivity and optical purity and further transformations on products.