Acetic acid glyceric aldehyde

A mixture of 50 g. (0.3 mole) of dZ-glyceric aldehyde acetal (p. 52) and 500 cc. of 0.1 N sulfuric acid is allowed to stand for one week at about 20 0 (Note 1). The mixture is then treated with 30 cc. of glacial acetic acid and neutralized carefully with barium hydroxide solution (Note 2). The mixture is stirred with 5 g. of decolorizing carbon and filtered. The filtrate is evaporated at 10 mm. pressure (Note 3). When no more water can be removed, the residue is treated with an equal volume of absolute alcohol to hasten crystallization. The crystals are collected on a filter and dried in a vacuum desiccator over soda-lime and calcium chloride. The yield of product melting at 137-1390 is 22 g. (80 per cent of the theoretical amount) (Note 4). 

After reduction of the enal with diisobutylaluminium hydride, the Wittig olefination of D-glycer-aldehyde acetonide (7 )-24 with Ph3P=CHCHO gives the ( )-allylic alcohol 129. The Katsuki-Sharpless enantioselective epoxidation [89] applied to 129 allows the preparation of D-arabinitol (= D-lyxitol) and ribitol, a meso alditol (Scheme 13.47). Similarly, Wittig olefination of R)-2A with Ph3P=CHCH(OEt)2, followed by acidic hydrolysis of the diethyl acetal and subsequent reduction of the enal with diisobutylaluminium hydride, provides the (Z)-allylic alcohol 130. Diastereoselective epoxidation and hydrolysis leads to D-arabinitol or xylitol, another meso alditol [90a]. 

At this point, to complete the subject of the radical oxidation of substituted carboxaldehydes, mention should be made of the findings concerning glyceric aldehyde [43], In the aqueous phase, the oxidation of this compound is a chain reaction. The accumulation of intermediate products such as glyceride and glycolic acids at the same time as acetic and formic acids and C02 indicates that this aldehyde has two reactive oxidation sites, i.e. the carbonyl group and the carbon a to this group. 

Glutamic acid, 10, in Glutaric AdD, 10, S8 (W-Glyceric aldehyde, 11, SO d/-GLYCERIC aldehyde ACETAL, 11, JO) S2... 

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