O-methylasparvenone, a nitrogen-free serotonin antagonist.

O-Methylasparvenone (1) and asparvenone (2) were isolated from an Aspergillus parvulus Smith broth in a microbial screening for 5-HT2C ligands and found to be 5-HT2C antagonists. They represent the first nitrogen-free serotonin ligands. The absolute configuration of 1 was determined to be S by X-ray analysis of the corresponding Mosher-ester. A short and efficient synthesis of rac-1 was developed. This protocol was applied to the synthesis of derivatives of 1 and a structure-affinity relationship was established.