An Improved Synthesis of 24, 24-Difluoro-1α, 25-dihydroxyvitamin D3 from Readily Available Vitamin D2

Kaori ANDO; Fumiaki KOIKE; Fumihiro KONDO; Hiroaki TAKAYAMA

doi:10.1248/cpb.43.189

An Improved Synthesis of 24, 24-Difluoro-1α, 25-dihydroxyvitamin D₃ from Readily Available Vitamin D₂

Kaori ANDO, Fumiaki KOIKE, Fumihiro KONDO, Hiroaki TAKAYAMA

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Keywords: 24, 24-difluoro-1α, 25-dihydroxyvitamin D₃, vitamin D₂-SO₂ adduct, Horner-Emmons reaction, α-keto ester, fluorination

JOURNAL FREE ACCESS

1995 Volume 43 Issue 2 Pages 189-192

DOI https://doi.org/10.1248/cpb.43.189

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Abstract

An improved synthesis of a highly potent vitamin D₃ analog, 24, 24-difluoro-1α, 25-dihydroxyvitamin D₃ (1b)has been accomplished via vitamin D₂-SO₂ adducts. The introduction of fluorine atoms was performed by treating the α-keto ester (11) with diethylaminosulfur trifluoride. The total yield was 12.5% from inexpensive vitamin D₂ in 11 steps. This sequence is sufficiently straightforward to be conducted on a gram scale.

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