Abstract
Studies on the chemical constituents of the flowers of Azadirachta indica have led to the isolation of two new flavanones, flowerine (=5‐hydroxy‐7,4′‐dimethoxy‐8‐(3‐methylbut‐2‐enyl)flavan‐4‐one; 1) and flowerone (=5,7,8,4′‐tetrahydroxy‐3′‐(3‐methylbut‐3‐enyl)flavan‐4‐one; 2), and two new triterpenoids, O‐methylazadironolide (=7__α__‐(acetoxy)‐23__ξ__‐methoxy‐21,23‐epoxy‐24,25,26,27‐tetranorapotirucalla‐1,14,20(22)‐trien‐3,21‐dione; 3) and diepoxyazadirol (=(20__S__,23__S__,24__R__)‐7‐α‐(acetoxy)‐25‐hydroxy‐21,24 : 23,24‐diepoxyapotirucalla‐1,14‐dien‐3‐one; 4) along with the known triterpenoid trichilenone acetate (=7__α__‐(acetoxy)‐14,15 : 21,23‐diepoxy‐24,25,26,27‐tetranorapotirucalla‐1,20,22‐trien‐3‐one; 5), two known flavanones, nimbaflavone (=5,7‐dihydroxy‐4′‐methoxy‐8,3′‐bis(3‐methylbut‐2‐enyl)‐flavan‐4‐one; 6) and 3′‐prenylnaringenin (=5,7,4′‐trihydroxy‐3′‐(3‐methylbut‐2‐enyl) flavan‐4‐one; 7), and 4‐(2‐hydroxyethyl)phenol (8). Their structures have been elucidated through spectral studies, including 2D‐NMR experiments, and chemical transformation. Compounds 5, 7 and 8 are heretofore unreported from any part of tree, while 6 has been isolated earlier from leaves.