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In this work we found that a H2O2–HBr(aq) system allows synthesis of α-monobromo ketones and α,α′-dibromo ketones from aliphatic and secondary benzylic alcohols with yields up to 91%. It is possible to selectively direct the process toward the formation of mono- or dibromo ketones by varying the amount of hydrogen peroxide and hydrobromic acid. The convenience of application, simple equipment, multifaceted reactivity, and compliance with green chemistry principles make the application of the H2O2–HBr(aq) system very attractive in laboratories and industry. The proposed oxidation–bromination process is selective in spite of known properties of ketones to be oxidized by the Baeyer–Villiger reaction or peroxidated with the formation of compounds with the O–O moiety in the presence of hydrogen peroxide and Bronsted acids.

A variety of vinyl sulfones were prepared from alkenes and sulfonyl hydrazides via electrochemical oxidative sulfonylation. The reaction proceeds in an experimentally convenient undivided electrochemical cell equipped with graphite and iron electrodes employing KI as a redox catalyst and a supporting electrolyte. Applying extremely high current density up to 270 mA/cm 2 permits rapid synthesis in a compact reactor and with small surface area electrodes. A possible reaction mechanism was proposed with the use of cyclic voltammetry. It is the combination of anodic and cathodic processes in this reaction that makes it possible to obtain products under mild conditions with yields from moderate to high.

A two-step, one-pot reaction of aldehydes with the CAN/LiBr oxidation system under solvent-free conditions followed by the addition of methanol affords methyl α-bromocarboxylates. The oxidation of aldehydes with methanol using this system gives only methyl esters. A facile method, which does not require special equipment, was developed for the synthesis of 2-bromoesters from aliphatic aldehydes with carbon chain lengths of 5–10 atoms.

The one-pot oxidation-chlorination of secondary alcohols to give α,α′-dichloro ketones in 62–80% yields is reported. The convenient and readily available H2O2/HCl system acts on secondary alcohols (C5-C17) with the formation of α,α′-dichloro ketones. The reaction proceeds with high selectivity under the reported conditions; during this process peroxide formation and the Baeyer-Villiger oxidation reactions are not observed.

Water was used as a reaction medium and a reagent in oxidation of primary alkanols to dimeric esters and alkanoic acids using either molecular bromine or a hydrogen peroxide—hydrobromic acid mixture as the oxidants. The similar reaction in methanol produced methyl alkanoates.

A new method for the synthesis of α-bromoketones was suggested. The C5-C11 linear and branched ketones in the reaction with the systems H2O2-LiBr-CeIII and H2O2-LiBr-CeIV in acetonitrile were brominated at α-position. The reaction is highly selective.

Reactions of alkenols with H2O2—LiBr—Ce(NO3)3·6H2O or H2O2—LiBr—Ce(NH4)2(NO3)6 system led to bromination of the double bond to yield vicinal dibromoalkanols. The reaction proceeded highly selectively, no oxidation of the hydroxyl group virtually occurred.

Action of a novel oxidation system, Ce(NO3)3·6H2O (cat.)-LiBr (cat.)-H2O2 (stoichiometric oxidant) on primary aliphatic C6–C9 alcohols gives selectively esters, whereas secondary aliphatic C5–C9 alcohols are converted into ketones. Selectivity of these transformations is provided by slow addition of H2O2 to the other reactants.

Oxidation of secondary alkanols with the system Ce(NH4)2(NO3)6—LiBr in aqueous acetonitrile gave ketones, α-bromo ketones, or α,α′-dibromo ketones. The selectivity of the reaction under standard conditions depends only on the molar ratio of the reagents (alkanol: CeIV: LiBr).

A method for the synthesis of “symmetric” esters based on the oxidation of primary straight-and iso-chain aliphatic alcohols C6 —C11 with the system Ce(SO4)2—LiBr in water has been suggested.

The solid-phase oxidation of cinnamic, 4-methoxy- and 3,4-dimethoxycinnamic acids with Ce(NH4)2(NO3)6—MHal system leads to β-halostyrenes. Similar procedure in the absence of a metal halide results in a cleavage of the C=C bond giving the corresponding benzaldehydes.

Esters are formed during the solvent-free oxidation of primary aliphatic C5–C9 alcohols with Ce(NH4)2(NO3)6–LiBr, whereas secondary octan-2-ol gives a mixture of isomeric 1-and 3-bromooctan-2-ones.

Solid state reactions of acids RCOOH (R = n-C7H15, BuC(Et)H, n-C9H19, PhCH2, PhCH2CH2, H2C=CH(CH2)8, or MeOOC(CH2)3) with Pb(OAc)4 combined with KCl, NaCl, CdCl2, or NH4Cl in the absence of a solvent and without mechanical activation afford chlorohydrocarbons RCl. The corresponding reactions of acids HOOC(CH2)nCOOH (n = 3–6) give dichloroalkanes Cl(CH2)nCl and γ-butyrolactone (n = 3).

A new procedure was developed for the introduction of the oxoalkyl fragment into N-heteroaromatic compounds of the pyridine and quinoline series. The procedure is based on the solid-phase reactions of lead tetraacetate with aromatic N-heterocycles and tertiary cycloalkanols.

Oxidation of linear or branched primary alkanols with H2O2-MBr (M = Li, Na, K)-HCl system in water affords the corresponding “symmetrical” esters in almost quantitative yield.

The mechanochemical oxidation ofn-pentanol,n-hexanol, andn-octanol with the Pb(OAc)4-MHal system (M=Li, K; Hal=Cl, Br) in the absence of a solvent affords esters. and secondary alcohols with the composition C8H17OH and C9H19OH give ketones.

The bromination of alkenols using the title H2O2—LiBr—Ce-systems proceeds highly selectively to furnish vicinal dibromoalkanols.

A simple, facile, and effective method for the synthesis of esters by the oxidation of linear and branched alkanols in water is presented.

Action of a novel oxidation system, Ce(NO3)3·6H2O (cat.)-LiBr (cat.)-H2O2 (stoichiometric oxidant) on primary aliphatic C6–C9 alcohols gives selectively esters, whereas secondary aliphatic C5–C9 alcohols are converted into ketones. Selectivity of these transformations is provided by slow addition of H2O2 to the other reactants.

Oxidation of primary and secondary alkanols to esters and ketones, resp., is achieved using a Ce(NO3)2—LiBr—H2O2 systems.

The oxoalkylation of pyridine, 2-methyl-, 4-methyl-, 2,4-dimethyl-, 2,6-dimethylpyridines, quinoline, 4-methylquinoline, isoquinoline, and pyrazine with oxoalkyl radicals generated from 1-methylcyclobutanol or 1-methylcyclopentanol under the action of Pb(OAc)4 or Mn(OAc)3 has been carried out. The reaction products are isomers with 2-(6)- and 4-positions of the oxoalkyl group in theN-heteroaromatic ring. The isomer ratios have been determined as a function of the structure of theN-heteroaromatic compound and the reaction conditions.

The manganese(III) acetate-mediated electrooxidative ring opening of 1-methylcyclobutanol (1) in acetic acid affords pentane-2-one (2) as the major product. The reaction of 1-methylcyclobutanol with Mn(OAc)3-LiCl gives 5-chloropentane-2-one (4.

A simple and efficient method for the synthesis of “symmetric” esters based on the oxidation of primary alcohols with cerium sulfate in combination with an alkali bromide is developed.

A mechanoactivated solid-state oxidative decyclization of 1-alkylcycloalkanols under the action of the Pb(OAc)4−MX or Mn(OAc)3−MX systems (MX is a metal halide) was carried out for the first time. The reaction affords exclusively ω-haloalkanones.

The main product of the reaction of 1-methylcyclobutanol with Pb(OAc)4 in benzene is 1-phenyl-4-pentanone; the use of Mn(OAc)3 in acetic acid gives a mixture of 2,9-decanedione and methyl propyl ketone; 1-(chloro-, bromo-, thiocyano-, or cyano)-4-pentanone is formed in the presence of the systems Pb(OAc)4-metal halide or Mn(OAc)3-metal halide.

The solid-phase oxidation of cinnamic, 4-methoxy- and 3,4-dimethoxycinnamic acids with Ce(NH4)2(NO3)6—MHal system leads to β-halostyrenes. Similar procedure in the absence of a metal halide results in a cleavage of the C=C bond giving the corresponding benzaldehydes.

The reaction of 2-butyl-3,3-(1′-heptyl)tetramethyleneoxaziridine with ferrous sulfate gave the N-butylamides of E- and Z-4-dodecenecarboxylic and E- and Z-5-dodecene-carboxylic acids in −1∶1 ratio. Analogously, 2-butyl-3,3-(1′-alkyl)pentamethy1-eneoxaziridines gave the N-butylamides of the corresponding E- and Z-unsaturated carboxylic acids.

A mechanoactivated solid-state oxidative decyclization of 1-alkylcycloalkanols under the action of the Pb(OAc)4−MX or Mn(OAc)3−MX systems (MX is a metal halide) was carried out for the first time. The reaction affords exclusively ω-haloalkanones.

Esters are formed during the solvent-free oxidation of primary aliphatic C5–C9 alcohols with Ce(NH4)2(NO3)6–LiBr, whereas secondary octan-2-ol gives a mixture of isomeric 1-and 3-bromooctan-2-ones.

A mechanically activated solid-state reaction of halogenation of naphthalene with a Pb(OAc)4—alkaline or alkaline-earth metal halide system was carried out to yield 1-halonaphthalene as the main reaction product and 1,4-dihalonaphthalene. The solid-state halogenation of naphthalene is more selective than a liquid-phase reaction.

The solvent-free decarboxylation of carboxylic acids by Pb(OAc)4 affords alkyl radicals, which alkylate 4-methylpyridine, quinoline, and 4-methylquinoline protonated with 2-chlorobenzoic acid. Mechanical activation is required for pyrazine alkylation.

The manganese(III) acetate-mediated electrooxidative ring opening of 1-methylcyclobutanol (1) in acetic acid affords pentane-2-one (2) as the major product. The reaction of 1-methylcyclobutanol with Mn(OAc)3-LiCl gives 5-chloropentane-2-one (4.

Solid-phase reactions and reactions in the absence of solvent have recently attracted considerable attention [1, 2]. We have already shown that the solid-phase reaction of protonated pyridine and 4-picoline with tertiary cyclic alcohols, which proceeds by the action of Pb(OAc)4, leads to the products of the oxoalkylation of these heterocyclic compounds in high yield [3]. However, the oxoalkylation of pyrazine could not be achieved under analogous conditions.

The title reactions of HOOC(CH2)nCOOH acids afford α,ω-dichloroalkanes (n = 3, 4, 6) and lactones (n = 3, 4) as the main products.

Solid-phase reactions and reactions in the absence of solvent have recently attracted considerable attention [1, 2]. We have already shown that the solid-phase reaction of protonated pyridine and 4-picoline with tertiary cyclic alcohols, which proceeds by the action of Pb(OAc)4, leads to the products of the oxoalkylation of these heterocyclic compounds in high yield [3]. However, the oxoalkylation of pyrazine could not be achieved under analogous conditions.

1. The LTA-Cu(OAc)2-mediated oxidation of tertiary cyclic alcohols produces cycloalkoxy radicals (R=alkyl; n=4–5), which undergo Β-fragmentation along two pathways: a) with ring opening to generate oxoalkyl radicals RCO(CH2)n-1CH2, which are oxidized quantitatively to Ω-unsaturated ketones, and b) with elimination of alkyl radicals (R.) and the formation of cycloalkanones. This reaction forms the basis for the synthesis of Ω-unsaturated ketones. 2. The relative rates for the two pathways of Β-decomposition depend upon the structure of the alkyl substituent. The frequency of Β-fragmentation via ring cleavage increases as the stability of the departing radical (R.) decreases: $$\dot CH_3< RCH_2 \dot CH_2< CH_3 \dot CH_2< (CH_3 )_2 \dot CH< (CH_3 )_3 \dot C< C_6 H_5 CH_2$$ . 3. The oxidation of 1-alkylcyclohexanols in which the alkyl groups exceed four carbon atoms results in the formation of alkoxy radicals which undergo oxidative cyclization and are converted into 2-alkyl-5-pentamethylenetetrahydrofurans.

As the result of the reaction of cyclopentanol and cyclohexanol with the Pb(OAc)4-LiCl and Pb(OAc)4-Cu(OAc)2 systems, ω-formylalkyl radicals CH2(CH2)n+1CHO (n=2, 3) are formed, which are oxidized by these systems into ω-chloroalkanals and ω-alkenals, respectively.

1. Cerium ammonium nitrate oxidizes 1-methyl- and 1-ethylcyclohexanol in aqueous acetonitrile in two directions, i. e., with elimination of the side alkyl group and with opening of the ring. 2. The oxoalkyl radicals formed during ring opening take part in hydrogen abstraction, rearrangement, recombination, and oxidation reactions. 3. During oxidation 1-methyl- and 1-ethylcyclohexanol partly react with acetonitrile by a earbonium ion mechanism to form N-(1-methylcyclohexyl)- and N-(1-ethylcyclohexyl)acetamide.

1. In the oxidation of primary, secondary, and tertiary aliphatic alcohols with the system Pb(OAc)4-metal chloride, the principal product is the δ-chloroalkanol. 2. EPR using spin traps has been used to identify the alkoxyl and secondary C-centered radicals generated in the oxidation.of an alcohol with Pb (OAc)4 and with the system Pb(OAc)4-LiCl.

1. As the result of the oxidation of C4-C7 1-methylcycloalkanols by the Pb(OAc)4-Cu(OAc)2 system, oxoalkyl radicals of type CH3CO(CH2)n+1CH2, n=1–4, are formed, which are quantitatively converted into unsaturated ketones CH3CO(CH2)nCH=CH2. 2. According to their reactivity in this reaction, 1-methylcycloalkanols can be arranged in the following series: C4>C5>C7>C6.

Secondary cyclic alcohols with C5-C8 ring size are oxidized by the lead tetraacetate-metal chloride or bromide system in three directions: with ring cleavage and the formation of ω-haloalkanals and without ring cleavage with the formation of the corresponding ketones and also, for C7-C8, 1,4-epoxycycloalkanes.

1. In the reaction of 2-, 3-, and 4-methylcyclohexanols with the Pb(OAc)4,-LiCl oxidizing system, methylcyclohexylalkoxyl radicals are generated, and their formation was confirmed by EPR with the use of a spin trap. 2. The 2- and 4-methylcyclohexylalkoxyl radicals are regioselectively rearranged into 1-methyl- and 3-methyl-5-formylamyl radicals, and the 3-methylcyclohexylalkoxyl radical decomposes in two directions, yielding 2-methyl- and 4-methyl-5-forraylarayl radicals. In the Pb(OAc)4-LiCl system, these radicals are quantitatively oxidized into chloroalkanals. 3. The trans-2 and cis-3-methylcyclohexanols exhibit higher reactivity with respect to the Pb(OAc)4-LiCl system than cis-2 and trans-3-methylcyclohexanols. The reactivity of both isomers of 4-methylcyclohexanol is the same.