Compounds of structural formula (I) where A is a lipophilic group including an aliphatic bridging group, B is a lipophilic group, D is a group having at least one amino or substituted amino group and R is hydrogen, alkyl or cycloalkyl, and pharmaceutically acceptable salts and individual isomers thereof, which have growth hormone releasing activity in humans or animals.
The green reaction of isatoicanhydrides with α-amino acids in presence of the ionic liquid 1-butyl-3-methylimidazolium bromide afforded 1,4-benzodiazepine-2,5-diones in excellent yields in absence of a catalyst. The reaction workup is simple and the ionic liquid was easily recovered from the reaction and reused. The methodology was quite general and a range of cyclic and acyclic α-amino acids were examined