Chemical studies of Kaempferia species and Costus lacerus (Zingiberaceae) and, synthetic utilitiies of [alpha]-Hydroxybenzylisoquinolines

Abstract

Chapter 1 Six novel pimarane-type diterpenes, sandaracopimaradien-9α-o1-1-one, sandaracopimaradien-1α, 9α -diol,6β-acetoxysandaracopimaradien- 1α,α9-diol, sandaracopimaradien-1α, 6β, 9α-triol, 6β-acetoxysandaracopimaradien-9α-o1-1-one and sandaracopimaradien-6β,9α -dio1-1-one,have been isolated from the rhizomes of Kaempferia species (Thai name: chung ngung; Family: Zingiberaceae). The structure of the diterpenes were established on the basis of their spectroscopic data and cheical studies. X-ray crystallographic analyses of sandaracopimaradien-1α,9α -diol and 6β-acetoxysandaracopimaradien-1α,9α -diol were carried out. Acid hydrolysis of the dry rhizome of Costus lacerus Gagn. (Family: Zingiberaceae) yielded diosgenin 1.7% the 95% ethanolic extract of the rhizomes gave β-sitosterol 3-O-β-D-glucopyranoside, prosapogenin A, dioscin and gracillin. Partial hydrolysis of gracillin afforded the new saponin, diosgenin 3-O-D-glucopyranosyl(1->3)-β-D-glucopyranoside. Chapter 2 The novel conversion of -hydroxybenzylisoquinoline derivatives to the corresponding aporphine alkaloids is reported. The route was exploited for the synthesis of various naturally-occurring aporphine alkaloids including thaliporphinemethine, wilsonirine, norpreocoteine, pancoridine and pontevedrine and pontevedrine derivative. The mechanism of the cyclization was proposed to be triggered by the carbonium ion generated at the benzylic position of-hydroxybenzylisoquinoline derivatives. Chapter 3 The reaction of-hydroxybenzylisoquinoline derivatives withboron trifluoride etherate in acetonitrile and benzene affordedthe imidazole derivatives in good yield. The synthetic andrnechanistic details of the reaction are discussed.