Kinetics of thermal [1,7a]-sigmatropic shift of hexafluoro vitamin D3 and vitamin D3 derivatives. Evaluation of conformations of the A ring affected by 1-OH and 3-OH groups.

The quantitative evaluation of the [1,7a]-sigmatropic rearrangement of vitamin D3 and its analogs affected by the conformations of the A ring using the 1H-NMR method was described. Although the side chain of the D ring had no effect on the hydrogen migration, the rearrangement was influenced by the hydroxy groups of the A ring.