Zur photosensibilisierten Autoxydation der Steroide: Δ⁵‐Steroid‐7α‐hydroperoxyde und ‐7‐ketone durch Allylumlagerung von Δ⁶‐Steroid‐5α‐hydroperoxyden

Abstract

Cholesterin (I a) geht bei der durch Hamatoporphyrin in Pyridin photosensibilisierten 02-Ubertragung zu 75 % d. Th. in das tertiare AWholesten-3 P-01-5 ahydroperoxyd (I1 a) iiber. Dagegen liefert die entsprechende Photooxydation in Chloroform das neue As-Cholesten-3 p-01-7 a-hydroperoxyd (111 a, 42 %d. Th.). -IIa und A6-Allopregnen-3 p-01-20-011-5 a-hydroperoxyd (I1 b) lagern sich in Chloroform sterisch einheitlich und fast quantitativ in IIIa bzw. As-Pregnen-3 P-01-20-on-7 a-hydroperoxyd (I11 b) um. D i e s neuartige Allylumlagerung von Hydroperoxyden, die in CHC13 durch Bestrahlen, Dibenzoylperoxyd oder Kupferhalogenide beschleunigt und durch Hydrochinon gehemmt wird, erfolgt iiber radikalische Zwischenzustande. Durch Abspaltung von Wasser aus den Hydroperoxyden I11 und als Hauptprodukte der katalysierten Umwandlung der Hydroperoxyde 11 entstehen die entsprechenden As-Steroid-7-ketone (V). PRAPARATIVE ALLYLUMLAGERUNGEN

Hydroperoxysterols from the Tunicate Eudistoma sp.

“…The hydroperoxysterols 1 and 2 had been prepared from cholesterol in 1973 15) and 1958, 16) respectively. The mechanism of the rearrangements of allylic hydroperoxides also have been proven.…”

“…The physical and spectral data of 2 are in full agreement with those reported previously. 16,19) Cytotoxicity Assays Steroids 1 and 2 were assayed for cytotoxicity against Hep3B, HepG2, A549, MCF7, and MDA-MB-231 tumor cells using the MTT method. 23) Freshly trypsinized cell suspensions were seeded in 96-well microtitre plates at densities of 5000-10000 cells per well with tested compound added from DMSO-diluted stock.…”

A Perspective on Free Radical Autoxidation: The Physical Organic Chemistry of Polyunsaturated Fatty Acid and Sterol Peroxidation

“…91 Brill subsequently reported the rearrangement of acyclic allylic hydroperoxides and confirmed that the mechanism proceeded by intermediate free radicals. 92 Very careful experiment work from the Beckwith and Davies groups on the cholesterol system made it clear that the [3,2] rearrangement had interesting mechanistic twists.…”

Mammalian Cells Engineered to Produce Novel Steroids

“…products, but no NMR data is available 22,23 . Selective 7β-hydroxylation of pregnenolones is possible with organic methods, but syntheses that favor 7α-hydroxylation do not appear possible 24 . While microbial pregnenolone 7α-hydroxylation has been described, the organisms make a mixture of products and the enzymes have not been identified [25][26][27] .…”