5090-61-9Relevant academic research and scientific papers
Iridium-catalysed highly selective reduction-elimination of steroidal 4-en-3-ones to 3,5-dienes in water
Li, Jide,Tang, Weiping,Ren, Demin,Xu, Jiaxi,Yang, Zhanhui
supporting information, p. 2088 - 2094 (2019/04/29)
Steroidal 3,5-diene is an important structural motif in steroid drugs. In this report, an iridium-catalyzed reduction-elimination of readily available steroidal 4-en-3-ones is realized to prepare steroidal 3,5-dienes. At a low catalyst loading (S/C = 200), heating 4-en-3-ones in a water-mixed organic solvent with formic acid without inert atmosphere protection afforded the desired 3,5-dienes in moderate to excellent yields. In a gram-scale preparation, recrystallization is used instead of column chromatography to purify products. Excellent functionality tolerance and regioselectivity are featured. Structural moieties such as alkanols (primary, secondary and tertiary), esters (except for formate), tolylates, and ketones (endocyclic or exocyclic) are not affected. Surprisingly, the reduction-elimination only takes place at A-ring 4-en-3-ones. In addition, bicyclic 4-en-3-ones are also viable substrates. Synthetic applications of steroidal 3,5-dienes are demonstrated. Our method can also lead to steroidal 3,5-dienes-3-d (>99% d-incorporation) when DCO2D and D2O are used together.
FRAGRANT SESQUITERPENES FROM AGARWOOD
Ishihara, Masakazu,Tsuneya, Tomoyuki,Uneyama, Kenji
, p. 1147 - 1156 (2007/10/02)
Two new sesquiterpene aldehydes, (-)-selina-3,11-dien-14-al and (+)-selina-4,11-dien-14-al, methyl ester derivatives of three new sesquiterpene carboxylic acids, (-)-methyl selina-3,11-dien-14-oate, (+)-methyl selina-4,11-dien-14-oate, and (+)-methyl 9-hydroxyselina-4,11-dien-14-oate, and a new nor-sesquiterpene ketone, (+)-1,5-epoxy-nor-ketoguaiene, have been isolated from Aquilaria agallocha (agarwood).Their structures have been established on the basis of detailed spectroscopic analyses and synthesis.The occurrences of dehydrojinkoh-eremol and neopetasane in agarwood were also confirmed by comparison of their mass spectral data and Rt on capillary GC with those of synthesized samples.The odoriferous properties of some natural and synthesized sesquiterpenes are also described. Key Word Index: Aquilaria agallocha; Thymelaeceae; agarwood; sesquiterpenes; (-)-selina-3,11-dien-14-al; (+)-selina-4,11-dien-14-al; selina-3,11-dien-14-oic acid; selina-4,11-dien-14-oic acid; 9-hydroxyselina-4,11-dien-14-oic acid; (+)-1,5-epoxy-nor-ketoguaiene; dehydrojinkoh-eremol; neopetasane.
The Rearrangement of Allylic Hydroperoxides Derived from (+)-Valencene
Davies, Alwyn G.,Davison, Ian G. E.
, p. 825 - 830 (2007/10/02)
(+)-Valencene (I) reacts with triplet oxygen to give 84 percent of the secondary β-hydroperoxyde (II) and 15 percent of the α-hydroperoxide (III); reaction with singlet oxygen gives principally (ca. 80 percent) the tertiary β-hydroperoxide (IV).This undergoes a Schenck rearrangement to give suprafacially the β-hydroperoxide (II) by a non-dissociative mechanism which does not involve exchange of oxygen in an atmosphere of 18O2.The hydroperoxide (II) then undergoes a slower Smith epimerization to the α-hydroperoxide (III) by a dissociative mechanism which involves a substantial (> 55 percent) exchange.
