Dibenzoyl tartaric anhydride

The dihydroxy lactone from L-threonic acid is prepared from L-dibenzoyl tartaric anhydride by catalytic hydrogenation over palladium. The substituted anhydride is formed from tartaric acid and benzoyl chloride. 

When tartaric acid (1) is heated with acetic anhydride or benzoyl chloride, the diacetyl tartaric anhydride 720a or the dibenzoyl tartaric anhydride 720b is obtained in excellent yield. 

The separation problem was solved by esterifying racemic 10 with succinic anhydride. The (R)-ester 145 now has a free carboxylic acid group and can be separated simply by extraction with weak base (NaHC03) without any chromatography. The ester is easily hydrolysed to (5)-(+)-10 which was obtained in 32% overall yield (maximum 50%) and 98.9% ee. They do not say whether they prefer this resolution to the classical version with dibenzoyl tartaric acid but both are good. 

Kafarski P, Lejczak B, Szewczyk J. Optically active 1-aminoalkanephosphonic acids. Dibenzoyl-L-tartaric anhydride as an effective agent for the resolution of racenuc diphenyl 1 aminoalkanephosphonates. Can. J. Chem. 1983 61 2425-2430. 

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