The mechanisms of the rearrangements of allylic hydroperoxides: 5α-hydroperoxy-3β-hydroxycholest-6-ene and 7α-hydroperoxy-3β-hydroxycholest-5-ene

Abstract

Both the Schenck (I) → (IIa) and Smith rearrangements (IIa) → (IIb) are studied.

Hydroperoxysterols from the Tunicate Eudistoma sp.

“…The mechanism of the rearrangements of allylic hydroperoxides also have been proven. [17][18][19][20][21][22] However, to the best of our knowledge, hydroperoxysterols 1 and 2 have not been isolated previously from any natural sources. The detailed assignments Cytotoxicity of metabolites 1 and 2 toward a limited panel of cancer cell lines was evaluated ( Table 2).…”

“…The physical and spectral data of 1 are in full agreement with those reported previously. 15,19) 7a-Hydroperoxycholesterol (2): White amorphous powder, 1 H-and 13 C-NMR data, see Table 1. The physical and spectral data of 2 are in full agreement with those reported previously.…”

“…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.…”

Cholesterol, Reactive Oxygen Species, and the Formation of Biologically Active Mediators

“…Furthermore, the 5␣-OOH-Ch product is metabolized at a lower rate, which helps explain the accumulation of this oxidized metabolite of Ch when singlet oxygen is exposed to cells (18). The initially formed 5␣-OOH-Ch is also known to rearrange to 7␣,␤-OOH-Ch upon sample work-up and possibly in situ in the membrane (6,19). These observations have led to the suggestion that measurement of 5␣-OOHCh could be a marker for singlet oxygen production within cells (17).…”

One-Pot Synthesis of (+)-Nootkatone via Dark Singlet Oxygenation of Valencene: The Triple Role of the Amphiphilic Molybdate Catalyst

“…As shown in Table 1, toluene gave the highest rearrangement rate in hydroperoxide 2. As previously reported, the hydroperoxide dimer combined by hydrogen bonding showed much lower activity than the free hydroperoxide [45,46]. The higher stability of hydroperoxide 2 in methanol can be explained by the hydrogen bond formation between the solvent molecule and the hydroperoxide function, which suppresses the rearrangement.…”