Short-Step Synthesis of Plant Growth-Promoting Brassinosteroids
キーワード:
Baeyer-Villiger oxidation
1984 年 32 巻 5 号 p. 2001-2004
詳細
1984 年 32 巻 5 号 p. 2001-2004
Brassinolide analogues, (22R, 23R, 24R)-2α, 3α, 22, 23-tetrahydroxy-B-homo-7-oxa-5α-ergostan-6-one (24-epibrassinolide) (10) and (22S, 23S, 24R)-2α, 3α, 22, 23-tetrahydroxy-B-homo-7-oxa-5α-ergostan-6-one (9), were synthesized from brassicasterol (3a) in five steps and with ca. 20% overall yield. The key steps are the direct formation of (22E, 24R)-3α, 5-cyclo-5α-ergost-22-en-6-one (4) from brassicasterol mesylate (3b), the acid-catalyzed rearrangement of 4 to (22E, 24R)-5α-ergosta-2, 22-dien-6-one (6), and the Baeyer-Villiger oxidation of the tetrahydroxy 5α-ergostan-6-ones 7 and 8.
