Schiff hase

Although there has heen a great deal of research concerning how platinum(II) complexes hind to biological molecules and the hkely mechanism of antitumor activity of these platinum-containing species, far less attention has heen paid to the properties of other metal complexes in this arena. Recent attention has fallen on cohalt(II)-Schiff hase complexes, as several have heen discovered to have promise as antiviral agents. A review of recent work has appeared elsewhere [64], so the topic will not he covered here however, in addition to focusing on recent developments, emphasis is placed on the introduction of the new head unit, 3,6-diformylpyridazine (13), into Schiff-hase macrocyclic electrochemistry. 

Pyridoxine is rapidly converted to pyridoxed phosphate in the liver tuid other tissues. Pyi idoxtd phosphate does not cross cell membranes, and efflux of the vitamin from most tissues is tis pyridoxed. Pyridoxal phosphate is exported from the liver hound to tdhumin hy formation of a Schiff hase to lysine (Zhang et ed., 1999). Much of the free pyridoxtd phosphate in the Uver (i.e., that which is not protein hound) is hydrolyzed to pyridoxed, which is also exported, emd circulates hound to hoth tdhumin emd hemoglobin in erythrocytes. 

Cytisine (VIII) was the starting point in a synthesis of angustifoline. Tetrahydrocytisine (XLI) was converted to the A -chloro derivative (XLII) with hypochlorite. The elimination of hydrogen chloride from the latter leads specifically to the Schiff hase (XLIII) which is stereospecifically alkylated with allyl magnesium chloride. The approach of the reagent from the under side of the molecule is sterically very improbable (52). 

Transaldolase has many features in common with the enzyme aldolase, which we met in the glycolytic pathway. Both an aldol cleavage and an aldol condensation occur at different stages of the reaction. We already saw the mechanism of aldol cleavage, involving the formation of a Schiff hase, when we discussed the aldolase reaction in glycolysis, and we need not discuss this point further. 

Mannich-type reaction of a,p-unsaturated ybutyrolactams with JV-Boc-imines in the presence of a preformed dinuclear nickel catalyst derived from a Schiff hase ligand. 

TETSUAKI OSAFUNE JEROME A. SCHIFF AND EIJI HASE ... 

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