Callistephin

Since a few protective groups cannot satisfy all these criteria for elaborate substrates, a large number of mutually complementary protective groups are needed and, indeed, are becoming available. In early syntheses the chemist chose a standard derivative known to be stable to the subsequent reactions. In a synthesis of callistephin chloride the phenolic —OH group in 1 was selectively protected as an acetate. In the presence of silver ion the aliphatic hydroxyl group in 2 displaced... 

The electrochemical and antioxidant properties of delphinidin, cyani-din, pelargonidin, kuromanin and callistephin were studied [60]. Antioxidant activities of the anthocyanins were evaluated using the l,l-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging method. The order of antioxidant activity of the five anthocyanins was delphinidin > cyanidin > pelargonidin > kuromanin > callistephin. 

Anthocyanins cyanidin chloride, callistephin chloride, pelargonin chloride, ideanin chloride, cyanin chloride and pelargonidin chloride (Prof. Liselotte Krenn, Vienna, Austria) were dissolved in DMSO. 

Anthocyanins isolated from plants were studied for their possible inhibitory action on the MDR1 efflux pump. Among anthocyanins tested in this study, only cyanidin chloride showed a slight inhibition on P-gp function (Table 9). The chlorides of callistephin, pelargonin, ideanin, cyanin and pellargonidin slightly enhanced the activity of the efflux pumps. 

Colchicine has one benzene ring and one aromatic seven-membered ring with six electrons (c count the electrons in the C=0 bond) as the delocalized structure makes clear. Callistephin h=j benzene ring and a two-ring oxygen-based cation, which is like a naphthalene. You can count it as cei ten-electron system or as two fused six-electron systems sharing one C=C bond, whichever you pre e ... 

Write mechanism arrows for the following step in the chemical synthesis by A. Robertson and R. Robinson (/. Chem. Soc. 1928, 1455—1472) of callistephin chloride, a red flower pigment from the purple-red aster. Explain why this transformation is a reasonable process. 

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