Ruff degradation

Problem 22.20 Two Ruff degradations of an aldohexose give an aldotetrose that is oxidized by HNO, to /n o-tartaric acid. What can be the family configuration of the aldohexose ... 

Problem 22.24 What monosaccharide is obtained from a Ruff degradation of o-mannose (Problem 22 11), the C epimer of o-glucose (Problem 22.23)7 ... 

Problem 22.28 An aldohexose (I) is oxidized by HNO, to a me o-aldaric acid (II). Ruff degradation of (I) yields (III), which is oxidized to an optically active dicarboxylic acid (IV). Ruff degradation of (III) yields (V), which is oxidized to l-( + )-tartaric acid (VI). Represent compounds (I) through (VI). M... 

Problem 22.60 Which D-pentose is oxidized to an optically inactive dibasic acid and undergoes a Ruff degradation to a tetrose whose glycaric acid is meso-tartaric acid ... 

The Ruff degradation,67 involving interaction of a salt of an aldonic acid, ferric acetate, and hydrogen peroxide, was employed in the synthesis of 5-deoxy-L-arabinose218 and 5-deoxy-L-Iyxose.219... 

In other work,540 it was found that, with one-quarter of an equivalent of sodium borohydride, 96 was regio- and stereo-selectively reduced in good yield to a >4 1 mixture of 28 and 48. This result contrasts with that of earlier work,529 in which it was reported that, on reduction of 96 with an excess of sodium borohydride, followed by a Ruff degradation of the mixture to the pentoses, D-arabinose (104) was the preponderant product, with a smaller proportion of L-xylose (23). This finding suggests that the reduction was stereoselective in the direction opposite to that actually observed in the later work. The methyl ester (115) of 96 has been selectively reduced with sodium borohydride, to afford methyl L-xi/Zo-2-hexulosonate as the major product.540... 

There are some reactions that use Fe(III) and H202 such as the Ruff degradation of aldonic acids [reaction (91) Moody 1964]. Here, Fe3+ only acts as a catalyst and free radicals seem not to be involved in this reaction. 

Two useful preparations of lower sugars by degradation of aldonic acids are discussed in the following Chapter. These are the traditional oxidation of salts of aldonic acids with hydrogen peroxide in the presence of ferric acetate (Ruff degradation) and the related oxidation of aldonic acids by hypochlorite, which was developed by Whistler and Schweiger.79... 

The first method employs the Ruff degradation of 3-methyl-D-glucose.26... 

Show that Ruff degradation of D-mannose gives the same aldopentose (D-arabinose) as does D-glucose. 

D-Lyxose is formed by Ruff degradation of galactose. Give the structure of D-lyxose. Ruff degradation of D-lyxose gives D-threose. Give the stmcture of D-threose. 

D-Altrose is an aldohexose. Ruff degradation of D-altrose gives the same aldopentose as does degradation of D-allose, the C3 epimer of glucose. Give the structure of D-altrose. 

The Kiliani-Fischer synthesis accomplishes the opposite of the Ruff degradation. Ruff degradation of either of two C2 epimers gives the same shortened aldose, and the... 

Kiliani-Fischer synthesis converts this shortened aldose back into a mixture of the same two C2 epimers. For example, glucose and mannose both undergo Ruff degradation to give arabinose. Conversely, the Kiliani-Fischer synthesis converts arabinose into a mixture of glucose and mannose. 

Ruff degradation of D-arabinose gives D-erythrose. The Kiliani-Fischer synthesis converts D-erythrose to a mixture of D-arabinose and D-ribose. Draw out these reactions, and give the structure of D-ribose. 

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