Efficient and Convergent Coupling Route for the Short-step Synthesis of Enantiopure 2α- and 2β-Alkylated 1α,25-Dihydroxy-19-norvitamin D3 Analogues - Yoshida, Akihiro; Ono, Keiichiro; Suhara, Yoshitomo; Saito, Nozomi; Takayama, Hiroaki; Kittaka, Atsushi (Synlett, 2003)