Reconfirmation of the structure of (+)-retamine from Lygos raetam Var. sarcocarpa by X-ray analysis

The structure of (+)‐retamine (1), which has been isolated from the aerial part of Lygos raetam var. sarcocarpa, has been reconfirmed by spectroscopic methods including two‐dimensional nuclear magnetic resonance spectroscopy and x‐ray analysis to be (+)‐12 α‐hydroxysparteine. The configuration of the hydroxyl group at the position 12 in (+)‐retamine and the intermolecular hydrogen bond in the crystal structure of (+)‐retamine have been established.