Richard R. Muccino

A route to tritium labelled 11-methyl prostaglandins

Labelled 11-methyl prostaglandins have been prepared via the catalytic tritium reduction of 11-iodomethyl intermediates. Two examples are reported for the preparation of such 11-iodomethyl precursors in which the desired lower side chain is attached in non-radioactive steps. Subsequent tritium hydrogenolysis of the 11-iodomethyl lactones followed by addition of the delta 5 cis-double bond yielded prostaglandins having specific activities of 10-15 Ci/mmol.

The synthesis of 25-hydroxy-cholecalciferol-23,23,24,24-t4 of high specific activity

Abstract Catalytic tritium reduction of cholest-5-en-23-yne-3β,25-diol diacetate ( VIII ) gave cholest-5-ene-3β,25-diol diacetate- 23 , 23 , 24 , 24 - t 4 ( IX ) having a specific activity of 92 Ci/mmol. Bromination, dehydrobromination and hydrolysis of the labelled material gave cholesta-5,7-diene-3β,25-diol- 23 , 23 , 24 , 24 - t 4 ( XI ) which was photolyzed to the previtamin and then thermally equilibrated to 25-hydroxy-cholecalciferol- 23 , 23 , 24 , 24 - t 4 ( I ).

[6] The preparation of l-ascorbic acid [35S]2-sulfate having a high specific activity

Publisher Summary The preparation of tracer levels of ascorbic acid [35S]2-sulfate generally involves the treatment of a 5,6-acetal of L-ascorbic acid with an amine-sulfur trioxide complex in a polar aprotic solvent. This chapter discusses the preparation of L-ascorbic acid [35S]2-sulfate having a high specific activity. The sulfation of 5,6-O-isopropylidene ascorbic acid (III) can be carried out more efficiently with sulfur trioxide in dimethylformamide. Removal of the 5,6-isopropylidene group is effected by passage of the labeled substrate (IV) through a column of Dowex 50 (H+) ion-exchange resin, a method that minimizes contamination of the product with inorganic sulfate. The resulting ascorbic acid [35S]2-sulfate can be crystallized as the dipotassium salt or as the barium salt; the insolubility of barium sulfate in water makes purification in this latter case much easier.