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Stereoselective synthesis of 1α-hydroxyvitamin D3 A-ring synthons by palladium-catalyzed cyclization

✍ Scribed by Kazuo Nagasawa; Yoshiro Zako; Hideki Ishihara; Isao Shimizu

Book ID
104225869
Publisher
Elsevier Science
Year
1991
Tongue
French
Weight
163 KB
Volume
32
Category
Article
ISSN
0040-4039

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✦ Synopsis

Palladium-catalyzed cyclization of 8-bromo-2,8-nonadienoates proceeded stereoselectively to give I cchydroxyvitamin D 3 A-ring synthons in good yields. l(x,25-Dihydroxyvitamin D 3 is known as the hormonaUy active form of vitamin D 3. Recently this hormone was found to induce cell differentiation of myeloid leukemia cells in addition to the role in calcium regulation, l) Since these potent biologically activities, a lot of synthetic efforts for la,25-dihydroxyvitamin D 3 have been made. 2) On the basis of Lythgoe's synthesis of vitamin D 3, Hoffman la Roche's group achieved the synthesis of let,25-dihydroxyvitamin D 3 using 2e as a useful precursor of A-ring synthon. 3) So far several synthetic methods for A-ring synthons starting from readily available chiral cyclohexanes have been reported, 4) but cyclization of acyclic compound has scarcely been reported. The latter has potent possibility to obtain vari-

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