Total Synthesis of the Proposed Structure of Uncarialin A.

The stereoselective total synthesis of the proposed structure of a potent serotonin 5-HT1A receptor agonist uncarialin A (1) is described. By employing the readily available meroquinene tert-butyl ester as the chiral synthon, the target structure has been prepared in a six-step linear sequence with a 17% overall yield. In comparison to the sample isolated from natural sources, the synthetic product shows significant spectral differences, strongly suggesting that the structure of the natural product should be revised.