Tartaric acid, configuration oxidation

Osmium tetroxide oxidation of (- )-( )-cyclooctene (6) afforded the ( + )-diol 7 whose absolute configuration was related to that of (+ )-tartaric acid (9) via the (+)-dimethoxy derivative 8. The (R)-configuration assigned by this correlation has been confirmed by a number of direct or indirect approaches. 

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 ... 

For a long time, this reaction was conducted exclusively with acety-lated nitriles of aldonic acids, and the products obtained were known in general as "aldose-amides. Fischer2 used this reaction to transform tetra-O-acetyl-L-rhamnononitrile into l,l-bis(acetamido)-l,5-dideoxy-L-arabinitol, whose subsequent hydrolysis and oxidation allowed him to determine the configuration of dextro-tartaric acid (L-threaric acid). 

The tetrose, D-erythrose, so obtained can be oxidized with nitric acid to meso-tartaric acid. Show how this information can be organized to establish the configurations of D-arabinose, D-ribose, ribitol, and D-erythrose. 

Degradation of (H-)-xylose by the Ruff method yields the tetrose ( —)-threose, which must therefore have configuration XIV. This is confirmed by oxidation of (— )-threose to optically active (— )-tartaric acid. 

It is interesting that Nef assigned the correct configurations to the D-galactometasaccharinic acids, as well as to the D-glucometasaccharinic acids, on the basis of analogies between the optical rotations of n-tartaric acid, the 2,4-dihydroxyglutaric acids (obtained by oxidation of the five-carbon metasaccharinic acids), and the 2,3,5-trihydroxyadipic acids (obtained by oxidation of the six-carbon metasaccharinic acids). 

An aide-memoire to assist in assignment of erythro and threo configurations is this if one takes erythrose (11), the product obtained after oxidation of both the CH2OH and CHO groups to COOH is meso-tartaric acid (9). 

Biotin is a hetero-bicycle with a urea and a thioether unit. It has three chiral centers. In synthesis one often starts with tartaric acid derivatives in order to produce the chiral sites at the ring junctions. me o-Dibromotartaric ester gives the desired cis configuration of a symmetrical bicycle, which becomes chiral upon introduction of the acid side chain. In one procedure the CHj groups of the thioether were activated by oxidation of the sulfur to the sulfoxide. Alkylation and removal of protecting groups gives the racemate. Separation of enantiomers occurs readily via the avidine molecular complex. 

Fischer projection formulas are often used to depict compounds such as glyceraldehyde, lactic acid, and tartaric acid. Draw Fischer projections for both enantiomers of (a) glyceraldehyde, (b) tartaric acid, and (c) lactic acid, and specify the (R) or (S) configuration at each chirality center. [Note that in Fischer projection formulas the terminal carbon that is most highly oxidized is placed at the top of the formula (an aldehyde or carboxylic acid group in the specific examples here).]... 

The absolute configuration of natural l-( -f- )-laudanosine was determined by chemical correlation with l-( — )-iV-norlaudanosine (LXXVI) whose configuration was established by oxidative degradation. Resolution of racemic LXXVI with V-acetyl-L-Ieucine gave the levorotatory base [oil, bp 210° [a]j> —13.3° in EtOH —21° in CHCI3 B HCl, mp 167° [a]i) -f 38° in H2O]. From the mother liquors the enantiomer was obtained by using di-p-toluoyl-L-tartaric acid -1-13° —21°). 

Resolution of l- -propo5y-3-methyl-3-phospholene 1-oxide (754) using TADDOL derivatives (755) or Ca salts of 0,0 -dibenzoyl-(2R,3R)- (756a) or 0,0 -di-p-toluoyl-(2R,3)-tartaric acid (756b) has been developed (Scheme 212). Both antipodes of l-n-propo qr-3-phos-pholene 1-oxide (754) have been obtained with ee >96% by exploiting the different antipode preference of the TADDOL derivatives (755). The absolute configuration of the 3-phospholene oxide (754) enantiomers has been determined by CD spectroscopy, assisted by TD-DFT quantum chemical calculations. Moreover, it has been found that the solvent used for resolution had a significant effect on the efficiency of the resolutions. ... 

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