Kinetic study of the epoxidation of alkenes by iodosylbenzene catalysed by iron(III) tetra(4-N-methylpyridyl)porphyrin in methanol

Inchley, Paul; Smith, John R. Lindsay

doi:10.1039/p29950001579

Cited by 8 publications

(8 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In some cases, complexes containing the hypervalent iodine within the coordination sphere of the metal have been forwarded as intermediates, and, in a few, cases iodosylbenzene adducts have been isolated (but not crystallographically characterized). [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] It has been demonstrated that the high solubility of these two materials in methanol arises from solvolysis to form (dimethoxyiodo)benzene and either water or p-toluenesulfonamide (eqs 2 and 3). 39,40 An equilibrium constant K s ) 0.7(1) at 27 °C was determined for eq 3.…”

Section: Introductionmentioning

confidence: 99%

“…Mechanistic studies of atom or group transfer reactions using PhIO or PhINTs have been complicated by the insolubility of these materials in organic media, leaving many unanswered questions about their role in metal-catalyzed oxidations. In some cases, complexes containing the hypervalent iodine within the coordination sphere of the metal have been forwarded as intermediates, and, in a few, cases iodosylbenzene adducts have been isolated (but not crystallographically characterized). − …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO₂Ar‘)

et al. 1997

View full text Add to dashboard Cite

Iodonium ylides of the form ArINSO 2 Ar′ (Ar ) m-tolyl, Ar′ ) p-nitrophenyl (1); Ar ) m-tolyl, Ar′ ) phenyl (2); Ar ) m-tolyl, Ar′ ) p-tolyl (3); Ar, Ar′ ) p-tolyl (4)) have been prepared and crystallographically characterized. Comparisons to previously structurally characterized members of this class of materials (PhINTs (Ts ) p-toluenesulfonyl), o-TolylINTs, MesINTs) demonstrate that apparently minor perturbations of the aromatic rings have substantial consequences on the supramolecular assemblies of these materials. The structures range from zigzag polymers (PhINTs, MesINTs), linear polymers (o-TolylINTs), layered structures (1), two-dimensional ladders (2, 3, o-TolylINTs), to even three-dimensional stepladders (4). Ab initio calculations for a model molecule, PhINSO 2 -Ph, corroborate the presence of a I-N single bond and show considerable charges being localized on the I, N, S, and O atoms (+, -, +, andcharges, respectively). Extensive attractive networks of I‚‚‚O and I‚‚‚N secondary bonds thus dominate the solid-state polymers. Within the monomeric units of ArINSO 2 Ar′, a U-turn-shaped motif is observed. This structural shape appears to optimize secondary bonding contacts between charged INSO 2 arrays. The structures of ArINSO 2 Ar′ have been systematically characterized.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO₂Ar‘)

et al. 1997

View full text Add to dashboard Cite

show abstract

“…It reacts with iodosylbenzene (Scheme 2) 14 giving (hydroxymethoxyiodo)benzene ( 7) and (dimethoxyiodo)benzene ( 8) and the former is thought to be the species that transfers oxygen to the metalloporphyrin to generate the active oxidant. 15 Furthermore, it is a competing substrate for the active oxidant and consequently epoxidation yields in methanol are generally lower than those in more robust solvents. 15 The particularly low epoxide yield from styrene with catalyst 1 probably arises from steric hindrance restricting the bulky iodosylbenzene derivative 7 from approaching the metal centre.…”

Section: Solvent Dependence Of the Enantioselective Epoxidation Of St...mentioning

confidence: 99%

“…15 Furthermore, it is a competing substrate for the active oxidant and consequently epoxidation yields in methanol are generally lower than those in more robust solvents. 15 The particularly low epoxide yield from styrene with catalyst 1 probably arises from steric hindrance restricting the bulky iodosylbenzene derivative 7 from approaching the metal centre.…”

Section: Solvent Dependence Of the Enantioselective Epoxidation Of St...mentioning

confidence: 99%

Asymmetric alkene epoxidation catalysed by a novel family of chiral metalloporphyrins: effect of structure on catalyst activity, stability and enantioselectivity

Smith

Reginato

2003

Org. Biomol. Chem.

View full text Add to dashboard Cite

A selection of alkenes has been epoxidised with iodosylbenzene, catalysed by three related iron(III) tetraarylporphyrins: 1*, 2* and 3* with four 2,6-di(1-phenylbutoxy)phenyl groups, with one pentafluorophenyl and three 2,6-di(1-phenylbutoxy)phenyl groups and with two pentafluorophenyl and two 2,6-di(1-phenylbutoxy)phenyl groups, respectively. 1* is very sterically hindered and prone to self-oxidation which makes it a relatively poor epoxidation catalyst. Introducing the smaller pentafluorophenyl groups, in place of 2,6-di(1-phenylbutoxy)phenyl, increases catalyst reactivity, stability and selectivity. This change allows easier access of the substrates to the active oxidant and also, by decreasing the electron density on the porphyrin ligand, increases the reactivity of the oxoiron intermediate and its stability towards self-oxidation. A family of five homochiral catalysts, 1, 2 and 3, [the analogues of 1*, 2* and 3*, prepared from (R,R)-2,6-di(1-phenylbutoxy)benzaldehyde] and catalyst 4 with three pentafluorophenyl and one (R,R)-2,6-di(1-phenylbutoxy)phenyl group and 5 the manganese(III) analogue of 3 have been used to epoxidise three prochiral alkenes. All the reactions give low enantioselectivities. Using styrene as the substrate, (S)-styrene epoxide is the major enantiomer obtained with all the catalysts except 1 which leads to the (R)-styrene epoxide being preferred. In contrast cis-hept-2-ene and 2-methylbut-2-ene give the same major epoxide enantiomer with all the catalysts. The dependence of the ee values on catalyst and substrate structure, temperature and solvent is examined and discussed.

show abstract

“…In this study acetonitrile was clearly the best solvent (Table 1). Methanol, unlike dichloromethane and acetonitrile, dissolves PhIO, 19 however, the epoxidation yields in methanol were disappointingly low and the yields of the unwanted PhIO 2 were high. It seems likely that the increased concentration of PhIO in methanol solution results in the formation of PhIO 2 at the expense of epoxycyclooctane from the competition between PhIO and cyclooctene for the active oxidant.…”

Section: Optimisation Of the Epoxidation Of Cyclooctenementioning

confidence: 99%

Alkene epoxidation with iodosylbenzene catalysed by polyionic manganese porphyrins electrostatically bound to counter-charged supports

Sacco

Iamamoto

Smith

2001

J. Chem. Soc., Perkin Trans. 2

View full text Add to dashboard Cite

Manganese() complexes of tetra-anionic and tetra-cationic porphyrins have been immobilised on counter-charged, surface-modified silica supports and on organic ion-exchange resins. The reactions of these supported manganese() porphyrin systems and analogous uncharged homogeneous systems have been examined using cyclooctene and (E)-and (Z)-4-methylpent-2-ene epoxidations, with iodosylbenzene (PhIO) as the oxygen donor.Comparisons using the manganese porphyrin systems as catalysts for the epoxidation of cyclooctene in acetonitrile reveal that, in low turnover reactions (maximum 136 turnovers), they all give an essentially quantitative yield of epoxide although the heterogeneous reactions are significantly slower than the homogeneous analogues. In large scale repeat-use experiments, however, the supported catalysts are clearly superior, giving markedly better yields.The epoxidations of (E)-and (Z)-4-methylpent-2-ene with all the catalysts show a very high stereoretention, with the (Z)-alkene reacting faster than the (E)-isomer. The sterically hindered manganese() 5,10,15,20-tetrakis-(2,6-dichloro-3-sulfonatophenyl)porphyrin (MnTDCSPP) shows the highest selectivity for the (Z)-isomer; by contrast the supported manganese() 5,10,15,20-tetrakis[2,3,5,6-tetrafluoro-4-(trimethylammonio)phenyl]porphyrin on Dowex (MnTF 4 TMAPP-Dowex) reacts with the two alkenes at effectively the same rate.The mechanism of the epoxidations and the influence of the porphyrin ligand and support on the substrate selectivity are discussed.

show abstract

Kinetic study of the epoxidation of alkenes by iodosylbenzene catalysed by iron(III) tetra(4-N-methylpyridyl)porphyrin in methanol

Cited by 8 publications

References 34 publications

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO₂Ar‘)

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO₂Ar‘)

Asymmetric alkene epoxidation catalysed by a novel family of chiral metalloporphyrins: effect of structure on catalyst activity, stability and enantioselectivity

Alkene epoxidation with iodosylbenzene catalysed by polyionic manganese porphyrins electrostatically bound to counter-charged supports

Contact Info

Product

Resources

About

Kinetic study of the epoxidation of alkenes by iodosylbenzene catalysed by iron(III) tetra(4-N-methylpyridyl)porphyrin in methanol

Cited by 8 publications

References 34 publications

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO2Ar‘)

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO2Ar‘)

Asymmetric alkene epoxidation catalysed by a novel family of chiral metalloporphyrins: effect of structure on catalyst activity, stability and enantioselectivity

Alkene epoxidation with iodosylbenzene catalysed by polyionic manganese porphyrins electrostatically bound to counter-charged supports

Contact Info

Product

Resources

About

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO₂Ar‘)

Secondary Bonding as a Force Dictating Structure and Solid-State Aggregation of the Primary Nitrene Sources (Arylsulfonylimino)iodoarenes (ArINSO₂Ar‘)