Alkenes hypochlorite

Reaction of HOCl, formed from calcium hypochlorite and CO2, with highly substituted alkenes in CH2CI2 is a convenient route to aHyUc chlorides (111). Ketones are chlorinated to a-chloroketones by reaction with HOCl Acetone initially gives CH2COCH2CI (112). Methyl ethyl ketone gives 78% CH3CHCICOCH3, 15% CH3CH2COCH2CI, and 7% dichlorides (113). 

Perhaps one of the most exciting developments in the chemistry of quinoxalines and phenazines in recent years originates from the American University of Beirut in Lebanon, where Haddadin and Issidorides first made the observation that benzofuroxans undergo reaction with a variety of alkenic substrates to produce quinoxaline di-AT-oxides in a one-pot reaction which has subsequently become known as the Beirut reaction . Many new reactions tend to fall by the wayside by virtue of the fact that they are experimentally complex or require starting materials which are inaccessible however, in this instance the experimental conditions are straightforward and the starting benzofuroxans are conveniently prepared by hypochlorite oxidation of the corresponding o-nitroanilines or by pyrolysis of o-nitrophenyl azides. 

Chlorohydnns and 1,2-dichloro denvatives are obtamed by oxidation of alkenes with fert-butyl hypochlorite when the reaction is performed in acetic acid instead of water, chlorohydrm acetate is formed [Ji] (equation 25)... 

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... 

Catalysis. Cytochrome P-450 model compounds catalyze the epoxidation of alkenes by hypochlorite ions.16 A typical catalyst is OMn(TMP)L+. 

The reaction of S03 with 1-alkenes is strongly exothermic and control of the reaction is difficult. In the past it was practice to bleach commercially prepared AOS to obtain acceptable Klett color. Chlorosultones, such as the 2-chloro-y derivative may be formed after addition of hypochlorite to the AOS. 

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... 

Nitrile oxides, which are formed by dehydration of nitroalkanes or by oxidation of oximes with hypochlorite,87 88 are also useful 1,3-dipoles. They are highly reactive and must be generated in situ.ss They react with both alkenes and alkynes. Entry 5 in Scheme 6.5 is an example in which the cycloaddition product (an isoxazole) was eventually converted to a prostaglandin derivative. 

An alternative method for dialkyl peroxide synthesis is the nucleophilic addition of an alkyl hydroperoxide to an alkene under acid catalysis reported by Davies and coworkers (Scheme 31, path B) ". A similar reaction is the nucleophilic addition of alkylhy-droperoxides to vinyl ethers under acid catalysis, producing perketals. Perketals can be deprotected under mild conditions (THF/water/acetic acid) and this hydroperoxide protection-deprotection sequence has been used by Dussault and Porter as a means for the resolution of racemic hydroperoxides (see also Section II.A.2) . In this respect more detailed studies were carried out with the perketals 75, which were prepared via reaction of alkyl hydroperoxides with vinyl ethers (Scheme 33). Weissermel and Lederer reported that in the presence of teri-butyl hypochlorite, a-chlorodialkyl peroxides can be formed in yields between 12% and 45% (Scheme 31, path C)". a-Alkoxydialkyl peroxides and diperoxyacetals were prepared by Rieche and coworkers via acid catalyzed reaction of one or two equivalents of alkyl hydroperoxides with acetals, ketals or aldehydes (Scheme 31, path D)" or by methylation of the corresponding a-alkoxy hydroperoxides with diazomethane (yields 11%, 27%)" . The diperoxyacetals 76 were isolated in yields ranging from 39 to 77%. 

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... 

Goals and five limitations in conjunction with the development of selective catalytic homogeneous oxidation systems are evaluated. Systems are presented that address several of the problems or goals. One involves oxidation of alkenes by hypochlorite catalyzed by oxidatively resistant d-electron-transition-metal-substituted (TMSP) complexes. A second involves oxidation of alkenes by H2O2 catalyzed by specific TMSP complexes, and a third addresses functionalization of redox active polyoxometalate complexes with organic groups. 

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