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A safe, rapid, and environmentally friendly synthesis of iodosylarene (ArIO) has been developed using NaClO under a carbon dioxide (CO2) atmosphere. Exposure of iodoarene to NaClO-5H2O in acetonitrile under CO2 (1 atm) resulted in the clean formation of ArIO within 10 minutes in high yield. The absence of a base in this method enables the direct use of in-situ-generated iodosylarene not only for a variety of oxidative transformations (synthesis of sulfilimine, pentavalent bismuth, benzyne adduct, etc.), but also for the synthesis of iodonium ylide and imino-λ3-iodane in one pot.

Preparation of vicinal halohydrins, in which copper or iron chlorides catalyze the ring-opening reaction of epoxides with visible light effectively, is described. The use of trichloroacetonitrile as a halogen source enables catalytic HCl generation under the mild conditions. This method can also be applied to the aziridine ring-opening reaction.

The synthesis of new chiral Lewis basic organocatalysts that contain pyridine N-oxide moieties fused with the bicyclo[3.3.1]nonane framework is reported. The obtained pyridine N-oxides were employed as catalysts in the enantioselective ring opening of meso-epoxides with silicon tetrachloride. Derivative 1b endowed with two 2,4-diaryl-substituted pyridine N-oxide moieties proved to be a particularly effective catalyst for desymmetrization of norbornene oxide 16i to furnish Wagner-Meerwein rearrangement product 20i in unprecedented 96 % ee. Difunctional congener 3, which is striped of the 4-aryl substituents, exhibited moderate to high levels of asymmetric induction (47-88 % ee) with alicyclic epoxide substrates. Chiral Lewis basic catalysts with pyridine N-oxide moieties fused with a bicyclo[3.3.1]nonane framework were used in the enantioselective ring opening of meso-epoxides. 2,4-Diaryl-substituted N-oxide exhibited excellent asymmetric induction with norbornene oxide (96 % ee), whereas less-substituted congener was most effective with alicyclic epoxide substrates (47-88 % ee).

1,3,2,4-Diazadiphosphetidines (P1-P3), as easily prepared, stable, and heterogeneous P(III) compounds, were used for the efficient conversion of epoxides to vic-halohydrins, vic-dihalides, or alkenes in the presence of different halogen sources in CH3CN. Of these phosphazanes, P3 is most suitable and contains 4 phosphorous atoms with the advantage of having greater atom economy and its phosphorus oxide byproduct can be easily separated from the reaction mixture by simple filtration. The nitrogen atoms in this molecule can also act as acid scavengers in the reaction.

An efficient and environmentally benign protocol for the synthesis of vicinal chlorohydroxy and chloromethoxy derivatives in a highly regioselective manner from olefins using NH4Cl as a chlorine source and oxone as an oxidant in aqueous acetone and methanol is demonstrated. This methodology offers an additive and metal chloride free approach and is endowed with simple reaction conditions, high yields a broad substrate scope and good functional group tolerance. Moreover, the aromatic substrates with a terminal double bond exhibited merely Markovnikov selectivity, while the internal alkenes show exclusive regiocontrol and low to moderate diastereoselectivity.

The stereoisomers of cis-2-halocycloalkanols were resolved by a kinetically controlled transesterification with vinyl acetate in the presence of lipases in organic media. High enantioselectivities (ee >98%) and good isolated yields were obtained for all substrates using the appropriate lipase. Burkholderia cepacia lipase was the most efficient enzyme for the resolution of these substrates. The enantiomeric purities of the compounds were defined by derivatization with Mosher's acid and the absolute configurations were determined by chemical correlation.

An efficient method for the synthesis of vicinal chlorohydrin or bromohydrin derivatives has been developed on the basis of direct halohydroxylation of various olefins with electrondonating or withdrawing substituent. The reactions were carried out under mild conditions in the presence of N-tosyl-l-threonine (NTsLT) as an acidic additive using chloramine T trihydrate, 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) or N-bromoacetamide (AcNHBr) as the halogen source, respectively, affording the corresponding vicinal halohydrins in good to high yields with excellent regio- and stereoselectivities.

An efficient and environmentally benign protocol for protective opening of epoxide (POE) with pivaloyl halides in solvent-free conditions and in aqueous media under catalyst-free conditions has been developed. The green reaction conditions, simple work-up procedures, high yields and broad scope of the reaction illustrate the good synthetic utility of this method. The key advantages of the reaction are regioselectivity and reconvertability of products into their prior epoxides in the presence of mild reaction conditions.

Efficient synthesis of protected and unprotected chlorohydrins has been achieved by ring opening of epoxides with acetyl/benzoyl chloride and TMSCl using a catalytic amount of ZnO as a reusable catalyst. The applicability of ZnO is further extended by performing the cleavage of the natural product 5,6-epoxysitosterol with acetyl chloride.

A new method is described for the mild and high regioselective conversion of epoxides to β-chlcrohydrins in high yields even in the presence of alcohols, carboxylic acids, oximes, amides, thiols and tetrahydropyranyl ethers using chlorodiphenylphosphine (ClPPh2) under solvent-free and neutral conditions at room temperature and in short reaction times. In addition, some other functional groups such as carbon-carbon double bonds, ester groups and also phenyl ring that are present in the epoxide molecules remain intact in this method.

"Chemical Equation Presented" PINDOX 8 has been identified as a chiral organocatalyst for the enantioselective ring-opening of cyclic meso-epoxides with SiCl4 to produce chlorohydrins In up to 90% ee. The catalyst Is most effective with saturated cyclic substrates containing more than seven carbon units.

Under acidic conditions zinc reduces diselenides to afford selenols, which can be either isolated or treated in situ with alkyl halides to produce alkyl selenides or with epoxides to give β-hydroxyselenides. Georg Thieme Verlag Stuttgart.

2,4,6-Trichloro-1,3,5-triazine (TCT, cyanuric chloride) was found to mediate the regio- and stereoselective ring opening of epoxides in H 2O in the presence of morpholine at room temperature to afford the corresponding β-chlorohydrins in excellent yields (Table). The transformation is very simple, fast, efficient, and ecologically beneficial.

Zirconyl chloride mediated regio- and stereoselective ring opening of epoxides and aziridines at room temperature affords the corresponding β-chlorohydrins and β-chloroamines, respectively in high yields. Copyright

The enantioselective ring opening of meso-epoxides (from both cyclic and acyclic olefins) with silicon tetrachloride under catalysis by chiral phosphoramides affords enantiomerically enriched chlorohydrins in excellent yields. Experiments designed to eluc

A variety of trans-β-substituted cyclic alcohols were stereoselectively chlorinated to either the corresponding cis-chloride or trans-chloride (inversion or retention of configuration) with good to excellent yields; the stereochemical outcome is determined by the size of the ring and the nature of the β-substituents, especially the electronegativity of the substituted atom. The Royal Society of Chemistry.

A simple, novel, and highly regioselective cleavage of epoxides into vicinal halo alcohols and symmetrical or unsymmetrical dihalides is described using different stoichiometries of triphenylphosphine (PPh3) and N-halo succinimide (NXS) or N-halo saccharine (NXSac).

Silphos as a silica-based phosphine [PCl3-n (SiO 2)n] provides a practical method for the conversion of epoxides to vic-haloalcohols in the presence of molecular bromine, iodine, or N-halosuccinimides (NXS, X = Cl, Br, I) in CH3CN or under solvent-free conditions at r.t. The simple filtration of heterogeneous Silphos oxide from the reaction mixture affords the pure vic-haloalcohols with excellent yields. Copyright Taylor & Francis Group, LLC.

(Chemical Equation Presented) Expanding the scope of enantioselective catalysis via DKR, transfer hydrogenation of a variety of cyclic α-halo ketones was accomplished using the Noyori/Ikariya (R,R)- or (S,S)-I catalysts and either HCO2H/Et3N or HCO2Na/n-Bu 4NBr in H2O/CH2Cl2 as the hydrogen sources. Good yields of vicinal bromo-, chloro-, and fluorohydrins with excellent de and ee levels were achieved in most cases after a simple tuning of reaction conditions.

Opening of epoxides can be an effective means by which a variety of functional groups can be incorporated. In this letter, we outline how variation of conditions, in particular, that of solvent and concentration, give rise to different products using the Lewis acid catalyst BiCl3.

Several epoxides are efficiently converted to the corresponding β-chlorohydrins in impressive yields with thionyl chloride in the presence of β-cyclodextrin using water as solvent at room temperature. Copyright Taylor & Francis, Inc.

A variety of structurally diverse epoxides undergo facile cleavages by ionic liquid, [AcMIm]X without any catalyst and solvent to produce the corresponding vicinal halohydrins in high yields. The cleavages are considerably fast and highly regioselective.

The environmentally benign, highly efficient synthesis of chlorohydrins by cleavage of epoxides using TMSCl in ionic liquid, bmimPF6, has been studied.

Epoxides undergo rapid ring-opening with lithium halides in [bmim]PF 6 or [bmim]BF4 ionic liquids under mild and neutral conditions to afford the corresponding vic-halohydrins in high to quantitative yields. The epoxides show enhanced reactivity in ionic liquids thereby reducing reaction times and improving the yields significantly. The recovered ionic liquid can be reused in three to four subsequent runs with consistent activity.

Epoxides were efficiently converted into the corresponding β-chlorohydrins in good yields by treatment with ZrCl4 in acetonitrile.

A new method is described for the efficient and selective conversion of epoxides to vic-halo alcohols or symmetrical and unsymmetrical dihalides using PPh3/DDQ/R4NX (X = Cl, Br, I) as a mixed-reagent system.

The preparation of diverse β-chloroethers, β-chloroacetates, and chlorohydrins is efficiently achieved under mild conditions by reaction of alkenes with trichloroisocyanuric acid (0.34 mol equiv) in alcohols (MeOH, EtOH, i-PrOH, t-BuOH), acetic acid or aqueous acetone, respectively.

Visible light irradiation of a reaction mixture of carbonyl-coordinated tetra(2,4,6-trimethyl)-phenylporphyrinatoruthenium(II) (RuIITMP(CO)) as a photosensitizer, hexachloroplatinate(IV) as an electron acceptor, and an alkene in alkaline aqueous acetonitrile induces selective epoxidation of the alkene with high quantum yield (Φ = 0.6, selectivity = 94.4% for cyclohexene and Φ = 0.4, selectivity = 99.7% for norbornene) under degassed conditions. The oxygen atom of the epoxide was confirmed to come from a water molecule by an experiment with H218O. cis-Stilbene was converted into its epoxide, cis-stilbeneoxide, without forming trans-stilbeneoxide, trans-Stilbene, however, did not exhibit any reactivity. Under neutral conditions, an efficient buildup of the cation radical of RuIITMP(CO) was observed at the early stage of the photoreaction, while an addition of hydroxide ion caused a rapid reaction with the cation radical to promote the reaction with reversion to the starting RuIITMP(CO). A possible involvement of a higher oxidized state of Ru such as RuIV, RuV, RuVI through a dismutation of the RuIII species was excluded by an experiment with RuVITMP(O)2. Decarbonylation of the Ru complex was also proven to be invalid. A reaction mechanism involving an electron transfer from the excited triplet state of RuIITMP(CO) to hexachloroplatinate(IV) and subsequent formation of OH--coordinated RuIII species, leading to an oxo-ruthenium complex as the key intermediate of the photochemical epoxidation, was postulated.

Micellar media are introduced for the efficient ring opening of epoxides with sodium salts of nucleophiles such as CN, N3-, NO3-, NO2, SCN, Br and Cl-, catalyzed with Ce(OTf)4. This method is an efficient procedure for the synthesis of different β-substituted alcohols under mild reaction conditions. The reaction with SCN- is an easy procedure for the high yielding preparation of epoxy sulfides.

(Matrix presented) In this study, it was demonstrated for the first time that a phosphazirconocene catalyzes the ring opening of epoxides with TMSCI. This reactivity leads to a facile preparation of chlorohydrins. The late transition metal Fe analogue was found to catalyze the reaction at rates and stereoselectivity comparable to those of the Zr complex.

Epoxides undergo rapid ring opening with cross-linked polyvinylpyrrolidone/thionyl chloride complex, under mild reaction condition to afford chlorohydrins in high yields.

Highly regioselective ring opening of epoxides to halohydrins has been carried out in impressive yields with hydrogen and lithium halides in presence of β-cyclodextrin using water as solvent.

An enantioselective ring opening of meso-epoxides with tetrachlorosilane in the presence of diisopropylethylamine exploiting chiral bipyridine N,N′-dioxides as catalysts affords the corresponding chlorohydrins in high enantioselectivities of up to 90% ee.

The O - H and C - O stretching frequencies of trans-2-halocyclohexanols in CCl4 solutions have been measured and theoretical calculations have been performed to elucidate the main interactions, which are responsible for the conformational equil

A wide variety of epoxides and aziridines were converted to the corresponding β-halohydrins and β-haloamines using cerium(III) chloride and the cerium(III) chloride/NaI system in acetonitrile. The reactions were highly regioselective and efficient with excellent yields under mild and neutral reaction conditions.

Epoxide ring opening is a frequently required transformation in Organic Synthesis. In this paper we describe the application of NbCl5 for this purpose using three different substrates. Chlorohydrins, 1,2-diols, products containing solvent resid

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We have succeeded in developing direct syntheses of trans β- azidohydrins and trans 1,2-diol derivatives from olefins catalyzed by dichlorotin oxide. The regioselectivity of these reactions with tri- substituted olefins is high (10:1 in the synthesis of 1,2-diol derivatives) to excellent (>99:1 in the synthesis of azidohydrins). It has been found that these reactions do not proceed via epoxides. (C) 2000 Elsevier Science Ltd.

Iron(III) trifluoroacetate was used as an efficient and nonhygroscopic catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides. The addition of chloride, bromide, iodide, and nitrate ions to epoxides to produce the corresponding 2-halo and 2-nitratoalkanols and also the conversion of epoxides to acetonides and thiiranes were also performed efficiently in the presence of this catalyst.

A range of tetrabutylammonium salts very efficiently catalyzes the azidolysis of epoxides with trimethylsilyl azide in a solvent-free process in good yields.

O,O'-Dibenzoyl-(2R,3R)-tartaric acid (DBTA) forms a hydrogen bonded supramolecular compound with alcohols. The supra-molecular compound formation is enantioselective for a large number of chiral alcohols, therefore DBTA can be used as resolving agent, also for compounds having no basic group. The condition of the complex formation is that the guest molecule should contain a proton donating group and a fitting aliphatic chain or cycloalkane ring. (C) 2000 Elsevier Science Ltd.

The use of quinuclidine N-oxide as a replacement for HMPA is described.

The reaction of epoxides with lithium halides was efficiently promoted on the surface of silica gel in the absence of any solvent to give the corresponding β-halohydrins. The reactivity of lithium halides was shown to follow the order LiI > LiBr >> LiCl, and the reactivity of LiCl was dramatically increased by adding an equivalent amount of water to this system. On the other hand a similar reaction with α,β-epoxyketones produces the α-haloenone derivatives, presumably via halohydrin intermediates. The epoxide-opening reaction of (R)-(+)-styrene oxide was also investigated to clarify the stereochemical features of this reaction.

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Ce(IV) as ceric ammonium nitrate can effectively catalyze ring opening of epoxides with halides under very mild conditions and easy procedure to give the corresponding β-chloro- and β-bromohydrins in excellent yields. The reactions occur with both substituted and unsubstituted quaternary ammonium halides and with high regio- and stereoselectivity. The reaction of optically active styrene oxide with chloride ion was found to be highly stereospecific and afforded the corresponding β-halohydrin in 96% ee.

SnCl2*2H2O-Mg and THF-H2O is an efficient system for the conversion of oxiranes into chlorhydrins.

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A novel manganese reagent, generated from KMnO4 and Me3SiCl, in the presence of a quaternary ammonium salt, is shown to smoothly dichlorinate alkenes, open epoxides and chemoselectively oxidise sulfides to sulfoxides.

FeCl3·6H2O absorbed on chromatographic silica gel can act as an efficient catalyst for alcoholysis, hydrolysis and acetolysis of epoxides. Methanolysis of (R)-styrene oxide proceeds with high stereospecificity and in excellent yield. This catalyst can also convert epoxides to their corresponding β-halohydrins and β-nitrato alcohols in the presence of chloride, bromide and nitrate ions respectively.