Total pentitol

The patient affected with RPI deficiency exhibits high concentrations of arabitol and ribitol (method 2) and total pentitols (method 1). 

Two total syntheses of pyrrolidine alkaloids have been reported. (—)-Codonopsinine (85), an imino-pentitol which exhibits antibiotic and hypotensive activity, has been synthesized in seven steps in 16% overall yield from dihydropyrrole 84. The enantioselective synthesis of the potent antifungal agent (-l-)-preussin (87) has also been achieved from L-phenylalanine derivative 86. The pyrrolidine skeleton was established by hydrogenolysis of an intermediate oxazoline and subsequent diastereoselective reductive cyclization of the resultant aminoketone using Pearlman s catalyst. ... 

The furoisoxazoline (8) has been used for the total synthesis of amino-deoxy pentose and pentitol derivatives, synthesis of the latter being outlined in Scheme 5. ... 

The methods of total synthesis used in the preparation of pentitols and hexitols are of interest because of the departure from the methods of classical carbohydrate chemistry. Illustrations are given above under the periti-tols and hexitols. The synthesis of glycitols from acetylene is commercially practical (see p. 242). 

The most important hexitols are o-glucitol and D-mannitol. The most important pentitol is xyhtol. The relative sweetness of both hexitols (in 10% solutions) and xyhtol, compared with saccharose, is about 60 and 100%, respectively. AU three polyols have very Kttle effect on blood glucose level and are therefore used as sweeteners for diabetics. However, their content must be included in the total energy intake. They exhibit mild laxative effects (such as prunes, which contain higher amounts ofglucitol than other fruits). 

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