A highly convergent synthesis of cryptophycins in their enantiomerically-pure forms was achieved. Our strategy consists of the synthesis of the two units 3 and 4 and linking them together to form the macrocyclic ring. The upper unit 3 was prepared from 10 in four steps, and the lower unit 4 was prepared from 20 in three steps. Enantioselective biocatalytic methodology was used to prepare the requisite chiral building blocks, (R)-11 and (R)-19. The stereochemical versatility of this synthetic approach is demonstrated by the synthesis of cryptophycin A and the four diastereomers of cryptophycin C.

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The Zimmerman reaction was found to be adaptable for the assay of prostaglandin synthetase, which is capable of catalyzing the conversion of arachidonic acid into 1 lcr-l5a-dihydroxy-9-oxo-5-cis,l3-truns-prostadienoic acid. The bovine seminal vesicle microsomes possess active prostaglandin synthetase activity when a heat-labile, nondialyzable inhibitor, present in the supernatant fraction was re-moved. Various parameters affecting the rate of this biosynthetic reaction have been quantitatively defined. To achieve maximal rate, both GSH and a cofactor must be present. The following compounds were found to be suitable cofactors: p-aminophenol, hydroquinone, L-norepinephrine, L-epinephrine, serotonin, and 5-hydroxyindolacetic acid. The p H optimum of this reaction depends on the specific coenzyme used.