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An optically active intermediate 5 for A-ring of 19-nor-1a,25-dihydroxyvitamin D3 2 has been synthesized in five steps, starting from readily available, inexpensive D(+)-xylose 6 with good yield.
An optically active intermediate 5 for A-ring of 19-nor-1a, 25-dihydroxyvitamin D3 2 has been synthesized in five steps, starting from readily available, inexpensive D (+) - xylose 6 with good yield.