D-ring allyl derivatives of 17β- and 17α-estradiols: Chemical synthesis and 13C NMR data

Abstract

We report the 13C NMR data for 17β-estradiol, 17α-estradiol, and a series of ten 17β- or 17α-estradiol derivatives bearing an allyl group on the D-ring (at C-17, C-16, and C-15 positions). The target 17β-OH estradiol derivatives were synthesized from estrone by well known methods to ensure the accuracy of the allyl stereochemistry. The 17α-estradiol derivatives were obtained by a modified Mitsunobu alcohol inversion of 17β-analogs. The carbon assignments were done using 1D and 2D NMR experiments. Six positions of the allyl group (17α, 17β, 16α, 16β, 15α, and 15β) and two alcohol stereochemistries (17β and 17α) of the D-ring were studied, resulting in an important source of data. The effect of allyl-positioning and alcohol stereochemistry on 13C NMR chemical shifts was also identified, producing important points of comparison for other steroid analogs.