Efficient and practical synthesis of the A-ring precursor of 19-nor-1alpha,25-dihydroxyvitamin D(3) and its (13)C- or (2)H-labeled derivative

A-ring hydroxymethyl 19-nor analogs of the natural hormone 1α,25-dihydroxyvitamin D3: synthesis and preliminary biological evaluation

A series 5-8 of 1- and 3-CH(2)OH 19-nor analogs of the hormone calcitriol (1) has been prepared. Surprisingly, 19-nor 1alpha-CH(2)OH analog 5a is more antiproliferative at 100 nM concentration than the corresponding regioisomeric analog 6a with the natural 1alpha-OH group, and 1alpha-CH(2)OH hybrid analog 7a is similar in antiproliferative potency to calcitriol (1) even at low nanomolar concentrations.

Novel synthetic approach to 19-nor-1alpha,25-dihydroxyvitamin D(3) and its derivatives by Suzuki-Miyaura coupling in solution and on solid support

19-nor-1alpha,25-Dihydroxyvitamin D(3) was synthesized by the Suzuki-Miyaura coupling of the A-ring intermediate 3, which was efficiently prepared from readily available 5-(tert-butyldimethylsilyl)oxycyclohex-2-enone (5), with the boronate compound of the C,D-ring portion. The method could be applied to a solid-phase synthesis to prepare the des-C,D derivatives of 19-nor-1alpha,25-dihydroxyvitamin D(3). [reaction: see text]