Chiral synthesis of the A-ring synthon 3 of 1α,25-dihydroxyvitamin D3 (1a) based on palladium-catalyzed cyclization of 8-bromo-2,8-nonadienoates is described. Reaction of (E)-4b and (Z)-4d in the presence of Pd(OAc)2, PPh3, and K2CO3 gave (E)-3b and (Z)-3d, respectively. Optically active 4d was prepared from 24 by asymmetric aldol reaction using 31, which was cyclized to 3d. With further reactions, 1α,25-dihydroxyvitamin D3 (1a) was obtained.
|ジャーナル||Journal of Organic Chemistry|
|出版ステータス||Published - 1993|
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