Alkenes sodium hypochlorite

The intramolecular cycloaddition of a nitrile oxide (a 1,3-dipole) to an alkene is ideally suited for the regio- and stereocontrolled synthesis of fused polycyclic isoxazolines.16 The simultaneous creation of two new rings and the synthetic versatility of the isoxa-zoline substructure contribute significantly to the popularity of this cycloaddition process in organic synthesis. In spite of its high degree of functionalization, aldoxime 32 was regarded as a viable substrate for an intramolecular 1,3-dipolar cycloaddition reaction. Indeed, treatment of 32 (see Scheme 17) with sodium hypochlorite... 

Sodium hexakis(formato)molybdate, 3, 1235 Sodium hypochlorite alkene epoxidation manganese catalysts, 6,378 Sodium ions biology, 6, 559 selective binding biology, 6, 551 Sodium molybdate, 3, 1230 Sodium peroxoborate, 3,101 Sodium/potassium ATPase, 6, 555 vanadate inhibition, 3, 567 Sodium pump, 6, 555 mechanism, 6, 556 Sodium pyroantimonate, 3, 265 Sodium salts... 

Ordinary alkenes (without an allylic OH group) have been enantioselectively epoxidized with sodium hypochlorite (commercial bleach) and an optically active manganese-complex catalyst. Variations of this oxidation use a manganese-salen complex with various oxidizing agents, in what is called the Jacobsen-Katsuki... 

Other metals can also be used as a catalytic species. For example, Feringa and coworkers <96TET3521> have reported on the epoxidation of unfunctionalized alkenes using dinuclear nickel(II) catalysts (i.e., 16). These slightly distorted square planar complexes show activity in biphasic systems with either sodium hypochlorite or t-butyl hydroperoxide as a terminal oxidant. No enantioselectivity is observed under these conditions, supporting the idea that radical processes are operative. In the case of hypochlorite, Feringa proposed the intermediacy of hypochlorite radical as the active species, which is generated in a catalytic cycle (Scheme 1). 

Attempts have been made to exploit the intrinsic C2 symmetry of the phenolate-based dinickel core in enantioselective catalytic reactions. Therefore, enantiomerically pure C2-symmetric ligands such as (736a) and the corresponding dinickel systems (736b) have been prepared ( Equation (27)),1890 and (736b) was tested in the epoxidation of unfunctionalized alkenes with sodium hypochlorite as the oxidant. The catalytic reaction was found to be highly pH dependent with an optimum at a pH of 9. While the complex is catalytically active, significant enantioselectivity was not achieved. 

In summary, the reaction of osmium tetroxide with alkenes is a reliable and selective transformation. Chiral diamines and cinchona alkakoid are most frequently used as chiral auxiliaries. Complexes derived from osmium tetroxide with diamines do not undergo catalytic turnover, whereas dihydroquinidine and dihydroquinine derivatives have been found to be very effective catalysts for the oxidation of a variety of alkenes. OsC>4 can be used catalytically in the presence of a secondary oxygen donor (e.g., H202, TBHP, A -methylmorpholine-/V-oxide, sodium periodate, 02, sodium hypochlorite, potassium ferricyanide). Furthermore, a remarkable rate enhancement occurs with the addition of a nucleophilic ligand such as pyridine or a tertiary amine. Table 4-11 lists the preferred chiral ligands for the dihydroxylation of a variety of olefins.61 Table 4-12 lists the recommended ligands for each class of olefins. 

A typical manganese-salen complex (27)[89] is capable of catalysing the asymmetric epoxidation of (Z)-alkenes (Scheme 18) using sodium hypochlorite (NaOCl) as the principle oxidant. Cyclic alkenes and a, (3-unsaturated esters are also excellent starting materials for example indene may be transformed into the corresponding epoxide (28) with good enantiomeric excess1901. The epoxidation of such alkenes can be improved by the addition of ammonium acetate to the catalyst system 911. 

Interesting results were obtained in the asymmetric epoxidation of the (Z)-alkenes 94 using the (salen)Mn catalyst 95 in conjunction with sodium hypochlorite as an oxidant, giving the optically active -epoxides 96 as the major products,1711 as... 

Epoxidation with sodium hypochlorite.1 Ni(salen), is an effective catalyst for oxidation of some alkenes with NaOCl under phase-transfer conditions. Styrenes... 

Quaternary ammonium tribromides can also be produced in situ from the quaternary ammonium bromide, sodium hypochlorite and sodium bromide and can be used, for example, in electrophilic addition reactions reaction with alkenes and alkynes. 

The stepwise formation of epoxides through the reaction of alkenes with sodium hypochlorite with, or without, the isolation of the intermediate chlorohydrin has been subjected to catalysis with (V-benzylquininium chloride under liquiddiquid two-... 

ELECTROPHILIC ADDITIONS TO CARBON-CARBON MULTIPLE BONDS A. Chlorinating agents Sodium hypochlorite solution 7V-Chloro succi n i m i de Antimony pentachloride Formation of chlorohydrins from alkenes Chlorination with solvent participation and cyclization Controlled chlorination of acetylenes... 

Recently, the intramolecular nitrile oxide-alkene cycloaddition sequence was used to prepare spiro- w(isoxazolines), which are considered useful as chiral ligands for asymmetric synthesis (321). Reaction of the dibutenyl-dioxime (164) (derived from the diester 163) with sodium hypochlorite afforded a mixture of diastereomeric isoxazolines 165-167 in 74% combined yield (Scheme 6.80) (321). It was discovered that a catalytic amount of the Cu(II) complex 165-Cu(acac)2, where acac = acetylacetonate, significantly accelerated the reaction of diisopropylzinc... 

The Mn(III) complex 31b was tested as a catalyst for the epoxidation of various alkenes using sodium hypochlorite or iodosylbenzene as oxidants. Although oxidation took place, no selectivity was observed. For example, allylresorcinol was not epoxidized with rates higher than that of allylbenzene. Presumably, the substrate is not bound in the cleft of 31b because the latter is occluded by methoxy groups. It is possible that the reaction occurs on the outside of the metalloclip, which cannot discriminate between guest molecules. 

The most widely used, and often most convenient reagents for such one-pot reactions are sodium hypochlorite (45) or hypobromite (16). These reactions are performed in the presence of an organic base (generally triethylamine) that normally enhances the yield of cycloaddition products (45). This method was employed for many intermolecular reactions (71) and also seems especially suited for intramolecular ones (72-77) as well as for the solid-phase synthesis (78) of 2-isoxazolines. Hypohalite can also be replaced by sodium bromite in combination with a catalytic amount of tri-n-butyltin chloride (79). In a related method, O-tributylstannyl oximes were treated with fert-butyl hypochlorite to produce nitrile oxides that were trapped with alkenes or alkynes to afford the corresponding isoxazolines or isoxazoles in moderate to good yield (80). 

Alkaline hydrogen peroxide oxidation52 has been extended to higher perfluorinated alk-1-enes, perfluorinated cycloalkenes and certain alkenes with internal C = C bonds.52 57 A convenient reagent for the preparation of perfluoroalkene epoxides is sodium hypochlorite in a mixture with aqueous acetonitrile or another aprotic solvent. Several cis- and traw.s-perfluoroalkenes are oxidized to 32 with retention of configuration (Table 4).58-63... 

The oxidations take place without affecting the sulfur atom when it is in one of its highest oxidation states (i.e., sulfur has an oxidation number of the value + 4 or +6, see Table 18). Thus, epoxidation of (pcntafluorosulfanyl)alkenes, e. g. 1, is achieved by treatment with sodium hypochlorite under phase transfer catalytic conditions.281... 

Hi) Epoxidation of alkenes by sodium hypochlorite An interesting epoxidation reaction of synthetic interest has recently been reported by Meunier and coworkers.483 The reaction of sodium hypochlorite with styrene catalyzed by Mn(TPP)X (X = Cl, OAc) under phase-transfer conditions affords styrene oxide in high yield (equation 213). 

The mechanism of the epoxidation of alkenes by the cytochrome P450 model, sodium hypochlorite-manganese(III) tetraarylporphyrins, involves rate-determining formation of an active species 234 from a hypochlorite-manganese complex 233 (Scheme 6) pyridine or imidazole derivatives, as axial ligands, accelerate this step by electron donation, although the imidazoles are destroyed under the reaction conditions368. 

Dimethylborane has been used to hydroborate alkenes regiospecifically. The resulting dimethylalkylborane reacted with ammonium hydroxide and sodium hypochlorite (generation of NH2C1 in situ) to yield isomerically pure alkylamines [21] (Table 2.1). 

Other Applications. Other (/ ,/ )-stilbenediamine derivatives have been used to direct the stereochemical course of alkene dihydroxylation (with stoichiometric quantities of Osmium Tetroxide and epoxidation of simple alkenes with Sodium Hypochlorite and manganese(III) complexes. ... 

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