Enantiospecific Synthesis and Biological Investigations of a Nuphar Alkaloid: Proposed Structure of a Castoreum Component

An enantiospecific synthesis of a nuphar alkaloid was achieved in nine steps from N‐Boc‐(L)‐proline. The alkaloid is a minor component of castoreum, which is secreted from the dried scent glands of a beaver. During the course of our study, the stereochemistry of three synthetic intermediates was verified by X‐ray crystal structure analysis, which helped to resolve the existing discrepancies among reports regarding the structure of this particular compound. On the basis of our synthesized alkaloid, we proposed the structure of the natural product. Also, intrigued by the therapeutic uses of castoreum, which was employed for gynecological purposes in ancient Greece and Rome, we conducted a biological screening and found that the alkaloid has affinity for the oxytocin receptor. The enantiospecific synthesis and biological activities of a nuphar alkaloid have been described. Reliable and scalable chemistry was used to synthesize the alkaloid in nine steps, and an affinity to three central nervous system (CNS) receptors, including the oxytocin receptor, was found.