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Paper | Special issue | Vol 61, No. 1, 2003, pp.327-338
Published online, 11th August, 2003
DOI: 10.3987/COM-03-S41
Synthesis of A-Ring Synthon of 2α-Substituted Vitamin D3 Analogues Utilizing Grignard Reaction towards Methyl 2,3-Anhydro-4,6-O-benzylidene-α-D-mannopyranoside

Shinobu Honzawa, Yasuhiro Yamamoto, Koshiro Hirasaka, Hiroaki Takayama, and Atsushi Kittaka*

*Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa 199-0195, Japan


A concise route to the Trost A-ring precursor enyne for synthesizing 2α-substituted 1α,25-dihydroxyvitamin D3 (1) is described, in which the 2α-substituents could be introduced via addition reaction of Grignard reagent towards the sugar epoxide, easily obtained from D-glucose. In the reaction, the solvent effect was remarkable and the use of toluene gave higher chemical yield and chemical reactivity as compared with ethereal solvents.