Part 1 describes the synthesis of ring A-oxygenated 6-aza steroids in the cholestane series. Methyl-5-oxo-5,7-seco-6-nor-3-cholesten-7-oate (89) was reacted with benzylamine to give N-benzyl-6-aza-2,4-cholestadien-7-one (88). Selective hydroboration of the 2,3-double bond of this compound yielded three alcohols which were identified as 3α-, 3β- and 2α-hydroxy-N-benzyl-6-aza-4-cholesten-7-one (91, 92 and 90 respectively). Oxidation of the first two with chromium trioxide in either acetone or pyridine gave N-benzyl-6-aza-4-cholesten-3,7-dione (93). In Part 2 the ORD curves of 6- and 11-aza steroids possessing lactam, enol lactam, and amide functions are discussed. All the compounds studied exhibited positive Cotton effects. An attempt is made to interpret the sign of the Cotton effects observed for the 6-aza steroid lactams in terms of the configuration at C₅. An investigation of the spores of Equisetum telmateia is described in Part 3. Equisporoside was isolated from the methanol extracts and shown to be identical with the known flavonoid, gossypitrin (22). It was concluded that the structure of equisetolic acid which was isolated from the ether extracts of the spores was HOOC(CH₂)₂₈C00H. This work corrects the previous formulations suggested for these compounds by other workers. The alkaloid content of the spores was found to be negligible. / Science, Faculty of / Chemistry, Department of / Graduate