1,5-Benzodiazepines (review)

Molecular iodine: A highly efficient catalyst for the synthesis of 7-arylbenzopyrano[1,3]diazepines in non-protic solvents

“…However, same reactions in non-protic solvents like dichloromethane and tetrahydrofuran leads to the formation of benzopyrano [1,3]diazepines with excellent yields (Table 3). Thus, it is concluded that formation of benzopyrano [1,3]diazepines are favoured only in the non-protic solvents. However, extent of polarity of solvents has not shown much effect on the formation of the desired product.…”

“…at room temperature. To our delight, we observed the formation of benzopyrano [1,3]diazepines 4a in 84% yields after 12 h (Scheme 1). Where as in the absence of catalyst, the reaction did not yield any product even after long reaction times.…”

“…As a part of our continuing effort in the laboratory toward the development of new methods [15] for expeditious synthesis of bioactive heterocycles compounds [16] and usage of iodine for organic transformation [17], we here in report a novel and efficient method for benzopyrano [1,3]diazepines scaffold using molecular iodine as a catalyst. This is a simple, rapid, one port and eco-friendly protocol for synthesis of annelated diazepines.…”

“…In protic polar solvents like methanol, ethanol the condensation of 4-hydroxycoumarin with benzaldehyde facilitates bis adduct 3,3 -phenylmethanebis- Table 2 Effect of temperature on iodine catalysed 7-arylbenzopyrano [1,3] (4-hydroxycoumarin) 5a (Scheme 2). However, same reactions in non-protic solvents like dichloromethane and tetrahydrofuran leads to the formation of benzopyrano [1,3]diazepines with excellent yields (Table 3). Thus, it is concluded that formation of benzopyrano [1,3]diazepines are favoured only in the non-protic solvents.…”

“…1,4-Diazepines are well known for their pharmaceutical properties. The discovery of diazepam followed by many other psychotropic agents sharing 1,4-benzodiazepines skeleton has also promoted the studies of the isomeric 1,5-and 1,3-benzodiazepines ring system [3]. In contrast, 1,3-diazepines are relatively little known [4].…”