Flueggedine, a novel axisymmetric indolizidine alkaloid dimer from Flueggea virosa

Flueggedine (1), a highly symmetrical [2+2] cycloaddition indolizidine alkaloid dimer, was isolated from the twigs and leaves of Flueggea virosa. Its structure with absolute configuration was elucidated by means of NMR and quantum approaches. The plausible biogenetic pathway of 1 was also proposed, which was further supported by biomimetic synthesis.