6-s-cis locked analogues of the steroid hormone 1α,25-dihydroxyvitamin D3. Synthesis of novel A-ring stereoisomeric 1,25-dihydroxy-3-epi-19-nor-previtamin D3 derivatives

1. Díaz, M.
2. Ferrero, M.
3. Fernández, S.
4. Gotor, V.