Alkaloids of Lindelofia macrostyla and a New Unsaturated Carboxylic Acid

Abstract

The new alkaloid lindelofamine N-oxide (1) and the known 1-exo-carboxypyrrolizidine (2) and the quaternary salt of the isoquinoline alkaloid O-methylarmepavine methyliodide (3) were isolated from Lindelofia macrostyla (Bunge) Popov for the first time. The structures were established by NMR spectroscopy, the absolute configuration was determined using X-ray diffraction analysis of the chiral centers of the last two as 1R,4R,8S and 1S, respectively. The new carboxylic acid (2S,3R)-2-hydroxy-2-isopropyl-3-{[(E)-2-methylbut-2-enoyl]oxy}butanoic acid, the structure and absolute configuration (2S,3R) of which were proven by NMR spectroscopy and an XSA, was also isolated.