Novel Partial Synthetic Approaches to Replace Carbons 2,3,4 of Steroids. A Methodology to Label Testosterone and Progesterone with 13C in the Steroid A Ring. Part 2

Fragmentation of the A ring of the steroid hormone testosterone to yield the 10-formyl-5-oxo-des A intermediate was achieved by lactolization, lactonization, ozonolysis, and oxidation of the resulting methylol group. The reconstruction of the A ring was carried out via a Wittig synthesis with triphenylphosphoranylidene-2-propanone-13C3. Syntheses of the ylide, of the 13C3-testosterone, and of 13C3-progesterone took place in acceptable yields.