Studies in natural products

• Main Author: Tele, Chhagan Godha
• Published: University of Aberdeen 1987
• Subjects: 547.7
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.593552

The first chapter of this thesis deals with some substitution reactions of -carbolines aimed at the synthesis of the metabolite 6-hydroxyharmine which is produced when harmine is incubated with rat liver microsomes. The conversion of 6-bromo- and 6-nitro-harmine into its hydroxy-analogue was not achieved but direct hydroxylation of harmine using lead tetra-acetate trifluoroacetic acid followed by in situ reduction with zinc dust gave 6-hydroxyharmine. This reaction also worked with harman and norharman. In the second chapter, the synthesis of 4-aryl-5,2'-oxido-coumarins has been carried out by oxidative coupling, using dichloro-dicyanobenzo-quinone or potassium ferricyanide on methoxy- or hydroxy-4-phenylcoumarins. Our synthesis of 4',5'-dihydroxy-7-methoxy-4-phenyl-5,2'-oxido-coumarin confirmed that one of the natural products isolated from Coutarea latiflora was indeed an oxido-coumarin. The third chapter examines the corrosion inhibitive properties on mild steel of naturally occurring organic compounds and their derivatives. Mono- and di-sodium salts of carboxylic acids, amino-acids, lignins, tannins and humic acids and extracts of the plants Crtisus scoparius (broom), Calluna vulgaris (heather), Pteridium aquilinum (fern), the seaweeds Fucus ceranoides and Pelvetia canaliculata and mussels Mytilus edulis all show indhibitor properties. An assessment of their relative efficiencies has also been made. The last part of this chapter discusses the corrosion inhibitive properties of oxidation products derived from castor and olive oils.