A biomimetic catalyst for the asymmetric epoxidation of unfunctionalized olefins with hydrogen peroxide

Epoxidation studies of 2-styrylchromones using jacobsen's catalyst and hydrogen peroxide and iodosylbenzene as oxidants

“…Only a few years after this key publication an asymmetric version of this epoxidation was reported by the groups of Jacobsen [18] and Katsuki [19] using chiral Mn(III)-salen complexes as catalyst. Iodosylbenzene [17][18][19][20][21][22][23] and sodium hypochlorite [24][25][26] are the most frequently used terminal oxidants but other oxygen sources such as hydrogen peroxide [27][28][29][30], dimethyldioxirane (DMD) [31][32][33], Oxone ® [34], tetrabutylammonium monopersulfate [35], tetrabutylammonium periodate [36], mchloroperoxybenzoic acid [37] and even molecular oxygen [38] have been reported. Iodosylbenzene is a polymeric substance, prepared by base-induced hydrolysis of the commercially available iodobenzene diacetate, and the role of the catalyst in homogeneous catalysis is to solubilise it in its monomeric form.…”

Three‐Membered Heterocycles. Structure and Reactivity

“…For example, by tethering an imidazole moiety to a chiral salen-type Mn(III) catalyst, an axial ligand is provided that imitates a peroxidase coordination sphere while still taking advantage of the asymmetric active site of the chiral (salen)Mn(III) species. The resulting catalyst (391, Figure 2.16) can be used at 10 mol.% loadings with dilute hydrogen peroxide as an oxidant [432]. In a similar vein, the chiral dicarbonyliminato manganese(III) complex 392 is effective using molecular oxygen as the terminal oxidant [433], and the manganese-picolinamide-salicylidene complex 393 exhibits excellent turnover using sodium hypochlorite [434].…”

Asymmetric epoxidation of chromenes catalyzed by chiral pyrrolidine SalenMn(III) complexes with an anchored functional group

“…[13,26] Berkessel et al have reported biomimetic asymmetric epoxidation using a manganese(Salalen) complex bearing an imidazole substitute at the C7 carbon, wherein the imidazole group was considered to coordinate at the apical position of the complex. [27] The axial coordination of the anchored imidazole group to the metal center was confirmed by ultraviolet-visible light (UV-vis) spectral analysis. In comparison to the UV-vis spectra of the complex 4 in dichloromethane, a red shift at the wavelength from 285 to 335 nm was observed in the spectra of the complex 1.…”