Kiliani, Heinrich

Keto-enol tautomerism, 264, 842-844 Kiliani, Heinrich, 994 Kiliani-Fischer synthesis, 994-995 Kimbail, George, 216 Kinetic control, 491 Kinetics, 362... 

Heinrich Kiliani (1855-1945) was born in Wiirzburg. Germany, and received a Ph.D. at the University of Munich with Emil Erlenmeyer. He was professor of chemistry at the University of Freiburg, where he worked on the chemistry of the heart stimulant drug digitoxin. 

Discovery of the chain-lengthening sequence was initiated by the observation of Heinrich Kiliani in 1886 that aldoses react with HCN to form cyanohydrins (Section 19.6). Emil Fischer immediately realized the importance of Kiliani s discovery and devised a method for converting the cyanohydrin nitrile group into an aldehyde. 

First, let us look at a method for converting an aldose into another aldose containing one more carbon atom, that is, at a method for lengthening the carbon chain. In 1886, Heinrich Kiliani (at the Technische Hochschule in Munich) showed that an aldose can be converted into two aldonic acids of the next higher carbon number by addition of HCN and hydrolysis of the resulting cyanohydrins. In 1890, Fischer reported that reduction of an aldonic acid (in the form of its lactone. Sec. 20.15) can be controlled to yield the corresponding aldose. In Fig. 34.2, the entire Kiliani-Ffscher synthesis is illustrated for the conversion of an aldopentose into two aldohexoses. 

In 1885, Heinrich Kiliani (Freiburg, Germany) discovered that an aldose can be converted to the epimeric aldonic adds having one additional carbon through the addition of hydrogen cyanide and subsequent hydrolysis of the epimeric cyanohydrins. Fischer later extended this method by showing that aldonolactones obtained from the aldonic acids can be reduced to aldoses. Today, this method for lengthening the carbon chain of an aldose is called the Kiliani-Fischer synthesis. 

The evidence that in natural products, especially in primary metabolites, some structural patterns are repeated in different structures, implies that most organisms have common biosynthetic pathways. At the end of the nineteenth century when the biosynthetic pathways were not known, Heinrich Kiliani and Hermann Emil Fischer developed a simple model which could explain how stereochemically pure long-chained monosaccharides can form from simple molecules. The simplest, parent monosaccharide is aldotriose with only one chiral carbon atom. Hence, there are D- and L-aldotrioses. Since aldotriose is the product of mild oxidation of glycerol it can also be called glyceraldehyde. 

Fischer made extensive use of the reactions of the sugars with phenylhydrazine, a reagent which he had discovered in 1875. Fischer also oxidised the sugars to mono- and dicarboxylic acids, reduced the carbonyl function to a hydroxyl group, and prepared lactones (cyclic esters) from the monocarboxylic acids. Fischer also used a reaction devised by Heinrich Kiliani (1855-1945) in which the carbon chain of a sugar could be extended. Thus a five-carbon sugar could be converted to two six-carbon sugars because a new asymmetric centre had been added. 

Heinrich Kiliani (1855 1945), professor, Ireiberg, Germany. Emil Fischer (1852-1919), professor, Berlin, Germany, Nobel Prize 1902. See Killiani, H. Chem. Ber., 1885,18,3066 and Fischer, E. Chem. Ber., 1889, 22,2204. 

In 1886, Heinrich Kiliani (University of Freiburg, Germany) observed that an aldose will react with HCN to form a pair of stereoisomeric cyanohydrins. 

This reaction is a modern variation of the Kiliani-Fischer synthesis (Emil Fischer, again, and Heinrich Kiliani, 1855-1945). In the first step, sodium cyanide (NaCN) adds to the ribose carbonyl group to make a cyanohydrin (p. 781). The key point is that a new stereogenic carbon is generated in this reaction and both (R) and (S) epimers will be formed. In other words, two products will be formed, one with the new OH group on the right in the Fischer projection and one with it on the left. 

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