Catalytic and asymmetric epoxidation of olefins with iron complexes of twin-coronet porphyrins. A mechanistic insight into the chiral induction of styrene derivatives

Chiral Atropisomeric Metalloporphyrins in the Enantioselective Styrene Epoxidation

“…[15] After chromatographic separation (alumina, CH 2 Cl 2 / MeOH, 90:10), the complexes were treated with dilute HCl affording the chloro iron porphyrins, 3a-d, in good yields. Each complex was characterised by UV/Vis, CD, IR and MS spectroscopy.…”

“…All the reactions were carried out following a standard procedure, [15] in which iodosylbenzene was used as a single oxygen-atom donor. Substrate, oxidant and catalyst were used in the ratio 1000:100:1 (1 mmol of olefin) and stirred in the dark at 0°C in dichloromethane as the solvent for about 3 h (Scheme 4).…”

Highly enantioselective epoxidation of styrenes: Implication of an electronic effect on the competition between spiro and planar transition states

“…Various chiral catalysts and reagents have been investigated for the epoxidation of styrenes, including chiral porphyrin complexes (16 -34), chiral salen complexes (35)(36)(37)(38)(39)(40)(41)(42), chiral oxaziridines and oxaziridinium salts (43)(44)(45)(46), and enzymes (47)(48)(49)(50)(51). Metal catalysts such as chiral porphyrin and salen complexes have been studied extensively for the epoxidation of these alkenes, and the enantioselectivities have reached the 80% range in a number of cases (21,23,29,31,37,38,40,41), with 96% enantiomeric excess (ee) being obtained in one case (3,5-dinitrostyrene) (23).…”

Enantioselective Hydrolysis ofo-Nitrostyrene Oxide by Whole Cells ofAspergillus nigerCGMCC 0496

“…They have recently been used to prepare photosensitive derivatives of biologically active compounds which can be studied in a complex system such as a living cell, 17) but the use of their optical form has been seriously hampered because no e‹cient way has existed to obtain them with high enantiomeric excess. The best results obtained have been a 46z yield with 89zee 18) for chiral o-nitrostyrene and a 37z yield with 47z ee for the corresponding diol 19) in previous reports. In the course of our work, the kinetic resolution of onitrostyrene oxide was studied as shown in Fig.…”