A Revised Structure for the Alkaloid, Tribulusterine, from Tribulus terrestris L.

The alkaloid tribulusterine, first obtained from the fruit of Tribulus terrestris L. and considered to be 1-[(3-hydroxymethyl)-2-furyl]-9H-pyrido[3,4-b]indole, has been shown by synthesis and spectroscopic analysis to be the (5-hydroxymethyl)-2-furyl analogue. This is the known beta-carboline alkaloid, perlolyrine. The synthesis of the 3-hydroxymethyl compound is discussed and its single crystal X-ray structure reported.