D-ring allyl derivatives of 17 beta- and 17 alpha-estradiols: chemical synthesis and 13C NMR data.

We report the 13C NMR data for 17 beta-estradiol, 17 alpha-estradiol, and a series of ten 17 beta- or 17 alpha-estradiol derivatives bearing an allyl group on the D-ring (at C-17, C-16, and C-15 positions). The target 17 beta-OH estradiol derivatives were synthesized from estrone by well known methods to ensure the accuracy of the allyl stereochemistry. The 17 alpha-estradiol derivatives were obtained by a modified Mitsunobu alcohol inversion of 17 beta-analogs. The carbon assignments were done using 1D and 2D NMR experiments. Six positions of the allyl group (17 alpha, 17 beta, 16 alpha, 16 beta, 15 alpha, and 15 beta) and two alcohol stereochemistries (17 beta and 17 alpha) 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.