The optical isomers of cis‐N‐normetazocine are the starting materials for the synthesis of a number of pharmacologically useful compounds. An improved resolution procedure for obtaining these isomers is reported.
Introduction
Metabolomics analysis depends on the identification and validation of specific metabolites. This task is significantly hampered by the absence of well-characterized reference standards. The one-carbon carrier 10-formyltetrahydrofolate acts as a donor of formyl groups in anabolism where it is a substrate in formyltransferase reactions in purine biosynthesis. It has been reported as an unstable substance and is currently unavailable as a reference standard for metabolomics analysis.
Objectives
The current study was undertaken to provide the metabolomics community thoroughly characterized 10-formyltetrahydrofolate along with analytical methodology and guidelines for its storage and handling.
Methods
Anaerobic base treatment of 5,10-methenyltetrahydrofolate chloride in the presence of anti-oxidant was utilized to prepare 10-formyltetrahydrofolate.
Results
Pure 10-formyltetrahydrofolate has been prepared and physicochemically characterized. Conditions toward maintaining the stability of a solution of the dipotassium salt of 10-formyltetrahydrofolate in solution have been determined.
Conclusion
This study describes the facile preparation of pure (>90%) 10-formyltetrahydrofolate, its qualitative physicochemical characterization, as well as conditions to enable its use as a reference standard in physiologic samples.
During the synthesis of deuterated 18-hydroxycortisol, two of the synthetic intermediates have been found to exist in tautomeric forms as the acyclic 18-hydroxy 20-ketone and the cyclic 18,20-hemiketal corresponding to the previously identified less polar (L) and more polar (M) forms of C-18 hydroxylated steroids, respectively. Specifically, p-chloranil oxidation of 18-hydroxycortisol-17,21-acetonide afforded two isomers of the 6,7-dehydro analogue; separate catalytic reduction of each isomer under deuterium gave a single isomer of acetonide-protected 18-hydroxycortisol-1,6,7-d 3 for each, with the more polar isomer giving a more polar product and the less polar isomer giving a less polar product. The more polar product (corresponding to M) was characterized as 18, 20hemiketal; 18-hydroxycortisol-17,21-acetonide-18,20-hemiketal-1,6,7-d 3 : in the deuterochloroform solution, it was found to slowly convert to a substance consistent with the hydroxy ketone structure with features resembling those of the isolated less polar isomer (corresponding to L). Deacetonidization of each gave 18-hydroxycortisol as a single product, which was characterized as the 18,20hemiketal. The issues associated with the existence of 18-hydroxysteroids as hydroxy ketones and hemiketals, both in solution and as isolable solids, are discussed.
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