Chemoselective epoxidation of electron rich and electron deficient olefins catalyzed by meso-tetraarylporphyrin iron(iii) chlorides in imidazolium ionic liquids

Abstract

The oxygenation of substrates containing both electron rich and electron deficient olefins (1a-b) catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides [TAPFe(III)Cl] with H 2 O 2 gave epoxides at both electron rich and deficient olefin (2a-b, 3a-b), while with iodosyl benzene (PhIO) gave the epoxides only at electron rich olefin (3a-b) in imidazolium ionic liquids (ILs). Further reaction of 2a-b with sodium hydroxide in methanol gave 4a-b by base catalysed rearrangement of enedione epoxides. Similar reaction of 4a-b with H 2 O 2 or PhIO gave the major epoxides of electron deficient olefins and electron rich olefins. The ferric peroxy anions (TAP-Fe III -OO À ) are effective intermediates in the epoxidation of electron deficient olefins, whereas the high valent oxoferrylporphyrin p-cation radicals (TAP-Fe IV QO + ) are involved in the epoxidation of electron rich olefins. The ILs provide the special microenvironments by the interactions of cations and anions, in which the generation of the active intermediates from TAPFe(III)Cl/[Bmim] [PF 6 ] and monooxygen donors could be accelerated significantly.

A Green and Versatile Route to Highly Functionalized Benzofuran Derivatives Using Biomimetic Oxygenation

“…Iron and manganese metaloporphyrins are known to be important models of CYP monooxygenases ,,,. These complexes are efficient catalysts for aromatic epoxidation reactions and studies of their reactions have led to important insights into the bioactivation of aromatics ,,.…”

Efficient oxidation of polycyclic aromatic hydrocarbons with H2O2 catalyzed by 5,10,15-triarylcorrolatoiron (IV) chloride in ionic liquids

“…The 1 H NMR spectrum of 17a in CDCl 3 on addition of CH 3 OH or in CD 3 (17) due to the axial ligand effect [19]. The catalyst 17a regenerates after removal of methanol/ACN as indicated by the 1 [8][9][10][11]. The UV-vis studies of 17a with ILs exhibited a red shift in the Soret band with enhanced absorption intensity (Figs.…”

“…Ionic liquids (ILs) have been used as a novel reaction media for various organic syntheses and transformations [4,5]. The positive effect of ILs on oxidation processes using iron and iron complexes has also been reported in literature [10,11]. Herein, we report the oxidation of 2-methyl naphthalene (1), naphthalene (2), anthracene (3) and benz [a] anthracene (4) with H 2 O 2 catalyzed by 5,10,15-triarylcorrolatoiron (IV) chloride [TACFe(IV)Cl] (17a-17e) in ILs (Scheme 1, Fig.…”