Brassinolide and its analogs. Part IV. Synthesis of brassinolide analogs with or without the steroidal side chain.
作者:Michitada KONDO、Kenji MORI
DOI:10.1271/bbb1961.47.97
日期:——
Four brassinolide analogs were synthesized starting from cholesterol, stigmasterol or pregnenolone. An analog possessing a hydroxyl group at C-17 instead of the steroidal side chain was only 0.001% as active as brassinolide upon lamina-inclination testing with rice seedlings, while other analogs were 1-2% as active as brassinolide. This indicates the indispensable role of the side chain for the plant growth-promoting activity of brassino-steroids.
Remote substituent effect on the regioselectivity in the baeyer-villiger oxidation of 5α-cholestan-6-one derivatives
作者:Suguru Takatsuto、Nobuo Ikekawa
DOI:10.1016/s0040-4039(00)81564-6
日期:——
The regioselectivity in the Baeyer-Villiger oxidation of 5α-cholestan-6-one derivatives was markedly affected by the substituents at C-1, 2 or 3 position which were located at γ or δ position from the reaction center c-6.
Synthesis of brassinosteroids and relationship of structure to plant growth-promoting effects
作者:Malcolm J. Thompson、Werner J. Meudt、N.Bhushan Mandava、Samson R. Dutky、William R. Lusby、David W. Spaulding
DOI:10.1016/0039-128x(82)90129-5
日期:1982.1
alpha-ethyl substituent at C-24. Similarly, of the synthetic precursor tetrahydroxy ketones of the brassinosteroids, those with 22 alpha-OH, 23 alpha-OH orientation (like brassinolide) and an alkyl group at C-24 were also the most active in both bioassays. The results indicate stringent structural features are required for a steroid to induce brassin activity. The structural requirements are: a trans A/B ring
Brassinosteroids with lactone B-ring (II and IV) were prepared by oxidation of the corresponding 6-keto derivatives I and III without protection of the hydroxyl groups against the action of the oxidation reagent.