PROTON ACID-INDUCED REARRANGEMENTS OF ALPHA-ALKYNYLESTRADIOL METHYL ETHERS

When subject to proton catalysis, the alpha-alkynylestradiol methyl et hers 1a and 1b furnish the Rupe or Meyer-Schuster rearrangement produc ts 2, 4, and 5a. In the presence of sulfuric acid, alpha-ethynylestrad iol 3-methyl ether (1a) is converted into the D-homosteroid 3a. The us e of deuterated acids gives rise to the formation of the corresponding deuterated steroids 2b, 2c, 3b, and 5b. Some mechanistic implications of these results are also discussed.