Tartaric acid, dibenzoate

Tartaric acid, dibenzoate, (-)-Orthoformate or diethoxymethyl acetate Cyclopropylamine... 

SYNS BUTANEDIOIC ACID, 2,3-BIS(BENZOYLOXY)-, (R-(R, R ))- TARTARIC ACID, DIBENZOATE... 

Due to the complexity of conformational equilibria, the application of the dibenzoate chirality rule to determination of the absolute configuration of acyclic diols and polyols requires cautious evaluation of the CD data. For example, (0,0)-dibenzoyl derivatives of diesters and N.N.N ,AT-tetraalkyldiamides of (/t,f )-tartaric acid give exciton Cotton effects of opposite sign due to the preference of diesters for a planar and tetraalkyldiamides for a gauche conformation of the carbon chain176. 

To determine the absolute configuration of optically active organic compounds, there are two nonempirical methods. One is the Bijvoet method in the X-ray crystallographic structure analysis, which is based on the anomalous dispersion effect of heavy atoms. - The X-ray Bijvoet method has been extensively applied to various chiral organic compounds since Bijvoet first succeeded in determination of the absolute stereochemistry of tartaric acid in 1951. The second method is a newer one based on the circular dichroism (CD) spectroscopy. Harada and Nakanishi have developed the CD dibenzoate chirality rule, a powerful method for determination of the absolute configuration of glycols, which was later generalized as the CD exciton chirality method. 8 The absolute stereochemistry of various natural products has been determined by application of this nonempirical method. 

The Bristol-Meyers Squibb company wanted the simple heterocycle 8 for the preparation of a tryptase inhibitor. As 8 is an amine, tartaric acid was the first choice for a resolving agent. It again turned out that a modified version of the first choice was the best. Tartaric acid is so good at resolutions that simple variations, such as the dibenzoate ester 9, often work well. 

Addition of a small proportion of iron (II) sulfate to D-tartaric acid-hydrogen peroxide causes rapid conversion into a product closely related to dihydroxymaleic acid. Occurrence of a reaction with substituted hydrazines indicates the presence of a keto acid (1), and isolation of a diacetate and a dibenzoate favors the hypothesis of formation of dihydroxy-fumaric acid (2). On the basis of pH studies, Hatcher and Sturrock ... 

At present there is a large amount of experimental data available - mostly X-ray dif action studies, (Stem and Beevers, 1950 Van Bommel, Bijvoet,1958 Tapscott et al., 1969 Rychlewska, 1992 Szczepahska et al., 1994-1995) VCD, (Polvarapu et al, 1985 Su and Keiderling, 1980) ROA, (Barron, 1978 Barron et al., 1992) NMR (Ascenso and Gil, 1980 Hasa, 1980) measurements and dibenzoate exciton chirality analysis (Gawrohski et al., 1989) for both ionic and covalent derivatives of (R,R)-tartaric acid (Fig. la). 

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