The crystal structure of platyphylline and molecular conformational analysis of integerrimine

The title compounds platyphylline (C(18)H(29)NO(5)0.5H(2)O) and integerrimi ne (C18H25NO6) have been isolated from the serial parts of the Senecio spec ies. The crystal and molecular structures of platyphylline have been determ ined. The compound crystallises in orthorhombic space group, P2(1)2(1)2(1), The pyrrolizidine nucleus exhibits exo-buckling conformation. The molecula r geometry was stabilized by C-H...O and C-H...N hydrogen bonds. A search f or the low energy conformations of integerrimine as a similar alkaloid was also carried out. Force field calculations were undertaken by the MM3 progr am and some particular conformations were computed with the semi-emprical m olecular orbital methods by the AMI and PM3 programs.