Hypochlorite reactions with alkenes

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. 

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 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. 

Boron trifluoride and boron trifluoride-diethyl ether complex can be used as a source of fluoride ions in the presence of hypobromites and hypochlorites, e.g. methyl hypobromitc, tert-butyl hypobromite, methyl hypochlorite in carbon tetrachloride at 25 C. The addition of bromine monofluoride" and chlorine monofluoride" to various alkenes is accompanied by the formation of the corresponding alkoxybromides and alkoxychlorides which hinder the isolation of the halofluorinated products.57 jV-Bromo- and A -chloro-substiluted alkyl- and arylamines. -amides, and -imides, A -chloro-A,-methylamine, A -bromo-A -methylamine, A -chloro-A, /V-dimethylamine, A-bromo-A.A-dimethylamine, ACV-dichloro-A -methylamine, V,fV-dibromo-,V-mcthylaminc, A -bromosuccinimide, -V-chlorosuccinimide, Af-bromoacct-amide, A.A -dichlorourethane, can be used in the reaction instead of the hypohalites. The reactions with various alkenes conducted in dichloromethane at room temperature in the presence of boron trifluoride-diethyl ether complex produce bromofluoro and chlorofluoro addition products in 40-80 % yield. However, the reactions are complicated by the addition of A -halo-succinimides and Af.A-dichlorourcthane to the C = C bonds.58... 

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 ene- pe chlorination, specific with this halogen atom, of alkenes would account for a somewhat different mode of halogen addition, giving usefiil allylic dilorides. Efficient and convenient reagents and methods develtqted are dichlorine monoxide (ChO equation 36), r-butyl hypochlorite, and electro-chemical reactions with chloride ion (equation 37). The ene-type chlorination proceeds smoothly with... 

Vicinal hydroxy carbamates are prepared by the osmium-catalyzed reaction of alkenes with A-chloro-A-metallocarbamates generated in situ from A-chloro-A-sodiocarbamates (easily prepared from the carbamate, tert-butyl hypochlorite, and sodium hydroxide in methanol) by reaction with silver nitrate77 or mercury(II) salts78 in acetonitrile, The greatest reactivity was, however, displayed by the A-chloro-A-sodiocarbamate/mercuryUI) nitrate/tetraethylam-monium acetate (relative ratio 1.5 0.75 1) system, unfortunately low yields of hydroxycarba-mates from trisubstituted alkenes were obtained, due to competitive formation of organomer-... 

The epoxidation of alkenes by sodium hypochlorite in the presence of manganese porphyrins under phase-transfer conditions has been thoroughly studied. Kinetic studies of this reaction revealed a Michaelis-Menten rate equation. As in Scheme 12, the active oxidant is thought to be a high-valent manganese( V)-oxo-porphyrin complex which reversibly interacts with the alkene to form a metal oxo-alkene intermediate which decomposes in the rate determining step to the epoxide and the reduced Mn porphyrin. Shape selective epoxidation is achieved when the sterically hindered complex Mn(TMP)Cl is used as the catalyst in the hypochlorite oxidation. ... 

Benzylisourea tosylate (1.6 g, 5 mmol) was oxidized to 3-benzyloxy-3-chloro-37/-diazirine with hypochlorite. A DMF solution (25 mL) of this diazirine was combined with condensed 2-methylpropene ( 50 mL), and then a solution of TBACN (2.68 g, 10 mmol) in DMF (20 mL) was added over 15 min to the vigorously stirred diazirine/alkene/DMF solution at — 65 to — 70 °C. A transient red color developed which then faded to yellow after 30 min. After 4 hat — 50 C, the reaction mixture was warmed tort, the 2-methylpropenc was allowed to escape, and the crude product was isolated by an ice-water quench, followed by pentane extraction. The product was purified by GC (SE — 30, 120°C) yield 170 mg (15%, based on isourea). 

In pursuit of biomimetic catalysts, metaUoporphyrins have been extensively studied in attempts to mimic the active site of cytochrome P450, which is an enzyme that catalyzes oxidation reactions in organisms. In recent decades, catalysis of alkene epoxidation with metaUoporphyrins has received considerable attention. It has been found that iron [1-3], manganese [4,5], chromium [6], and cobalt porphyrins can be used as model compounds for the active site of cytochrome P450, and oxidants such as iodosylbenzene, sodium hypochlorite [7,8], hydrogen peroxide [9], and peracetic acid [10] have been shown to work for these systems at ambient temperature and pressure. While researchers have learned a great deal about these catalysts, several practical issues limit their applicability, especially deactivation. 

When excess alkene is employed, the addition of the hypohalite to the alkene takes place more readily than the above-mentioned substitutive electrophilic dehalogenation reaction. Based on the structures of stereoisomers obtained from the reactions of hypochlorite with cis- and trans-CHF=CHF and trans-CHC =CllC a regio- and stereospecific syn-addition mechanism was suggested (equation 76). Methyl and trifluoromethyl esters of... 

Synthesis of Al-Chloroamines. The conversion of secondary amines to iV-chloroamines by reaction with NCS in ether or dichloromethane has many advantages over the use of aqueous hypochlorite, including ease of isolation. This method has been used repeatedly in the preparation of Al-chloroamines for alkene amination (eqs 12 and 13) and other reactions. ... 

Mn(III) sits neatly in a tetracoordinate pocket in the ligand, and catalyses the epoxidation of simple alkenes by sodium hypochlorite, NaOCl, ordinary domestic bleach. Best results are obtained when the alkenes are cis (although an alternative range of ligands, developed by Tsutomu Katsuki, work well with trans alkenes), and one of the most significant applications of the Jacobsen epoxidation is with indene, which gives an epoxide in 84% ee with <1% of the catalyst. The mechanism of the reaction is complex and not fully understood, although it probably involves a Mn(V) oxo species and may involve radical intermediates. 

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... 

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. 

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. 

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