521-17-5Relevant articles and documents
Microbial transformation of dehydroepiandrosterone (DHEA) by some fungi
Yildirim, Kudret,Kuru, Ali,Y?lmazer Keskin, Semra,Ergin, Sinan
, p. 465 - 474 (2020/11/12)
In this work, biotransformations of dehydroepiandrosterone (DHEA) 1 by Ulocladium chartarum MRC 72584, Cladosporium sphaerospermum MRC 70266 and Cladosporium cladosporioides MRC 70282 have been reported. U. chartarum MRC 72584 mainly hydroxylated 1 at C-7α and C-7β, accompanied by a minor hydroxylation at C-4β, a minor epoxidation from the β-face and a minor oxidation at C-7 subsequent to its hydroxylations. 3β,7β-Dihydroxy-5β,6β-epoxyandrostan-17-one 6, 3β,4β,7α-trihydroxyandrost-5-en-17-one 7 and 3β,4β,7β-trihydroxyandrost-5-en-17-one 8 from this incubation were identified as new metabolites. C. sphaerospermum MRC 70266 converted some of 1 into a 3-keto-4-ene steroid and then hydroxylated at C-6α, C-6β and C-7α, accompanied a minor 5α-reduction and a minor oxidation at C-6 following its hydroxylations. C. sphaerospermum MRC 70266 also hydroxylated some of 1 at C-7α and C-7β. C. cladosporioides MRC 70282 converted almost half of 1 into a 3-keto-4-ene steroid and then hydroxylated at C-6α and C-6β. C. cladosporioides MRC 70282 also reduced some of 1 at C-17.
Sensitized Aliphatic Fluorination Directed by Terpenoidal Enones: A "visible Light" Approach
Bume, Desta Doro,Harry, Stefan Andrew,Pitts, Cody Ross,Lectka, Thomas
, p. 1565 - 1575 (2018/02/09)
In our continued effort to address the challenges of selective sp3 C-H fluorination on complex molecules, we report a sensitized aliphatic fluorination directed by terpenoidal enones using catalytic benzil and visible light (white LEDs). This sensitized approach is mild, simple to set up, and an economical alternative to our previous protocol based on direct excitation using UV light in a specialized apparatus. Additionally, the amenability of this protocol to photochemical flow conditions and preliminary evidence for electron-transfer processes are highlighted.
Multiple Enone-Directed Reactivity Modes Lead to the Selective Photochemical Fluorination of Polycyclic Terpenoid Derivatives
Pitts, Cody Ross,Bume, Desta Doro,Harry, Stefan Andrew,Siegler, Maxime A.,Lectka, Thomas
supporting information, p. 2208 - 2211 (2017/02/23)
In the realm of aliphatic fluorination, the problem of reactivity has been very successfully addressed in recent years. In contrast, the associated problem of selectivity, that is, directing fluorination to specific sites in complex molecules, remains a great, fundamental challenge. In this report, we show that the enone functional group, upon photoexcitation, provides a solution. Based solely on orientation of the oxygen atom, site-selective photochemical fluorination is achieved on steroids and bioactive polycycles with up to 65 different sp3 C-H bonds. We have also found that γ-, β-, homoallylic, and allylic fluorination are all possible and predictable through the theoretical modes reported herein. Lastly, we present a preliminary mechanistic hypothesis characterized by intramolecular hydrogen atom transfer, radical fluorination, and ultimate restoration of the enone. In all, these results provide a leap forward in the design of selective fluorination of complex substrates that should be relevant to drug discovery, where fluorine plays a prominent role.
