Electroorganic synthesis

The present report demonstrates an efficient use of microwave-tetraethylammonium superoxide combination under non-aqueous conditions to bring about a mild and safe carbamation/thiocarbamation of amines, using carbon dioxide/carbon disulfide and methyl iodide.

cothodically initiated Michael addition of thiok to levoglucossn~ne using small currents produces the previously unknown &co add&Xl product in several im@ace& The n0rnul ayrhro irKDIner, identified as the kinetic pr0dIlct, ten& to be formed whm large currents are used. The slow, low curreot elsctroiysea promots equilibntti0n of the two forms 80 that eryrJn.0 can be converted to rhreo by the retro reaction sod readdition. Additknu to R-(+)-rpovabarrme and R-(-)-arvone are also repmted,

The electrochemical oxidation of dimethyl disulfide was investigated in acetonitrile and dichloromethane. The nature of the oxidation strongly depends on the nucleophilicity of the solvent. In acetonitrile a one-electron oxidation is observed and the consecutive species did not exhibit any reactivity towards aromatic compounds subject to electrophile substitution. On the contrary, the oxidation of dimethyl disulfide in methylene chloride afforded a two-electron process with the formation of a species consistent with CH 3 S +. Its reactivity towards phenols and aromatic ethers was confirmed and showed a selective monomethylsulfanylation in most of the cases.

We report here the facile synthesis of a new series of hydroxy-thioxoimidazole carboxylates in good yields using the cyanomethyl anion as an electrogenerated base which is formed when dry acetonitrile is electrolyzed at constant current, followed by addition of different thioureas and diazirine-3,3-dicarboxylate. The mechanism of the reaction, NMR shifts and IR are discussed and compared to density functional theory calculations.

New five‐membered oxazol‐2(3H)‐one heterocycles and 1,2‐diaroylhydrazines are obtained in good yield when 1,2‐dicarbonyl substrates are reduced at the cathode in N‐methyl formamide/LiClO4 as solvent‐supporting‐electrolyte system, and in the presence of arenediazonium salts. Electrochemical pathways are presented to involve a) cascade reactions: hydrogen atom abstraction from a solvent molecule, radical coupling reaction with substrate intermediate, and intramolecular migration of a methylamino group, to provide oxazolones or b) surprising C−C bond cleavage in the substrate radical anion, assisted by a diazonium salt, that evolves to disubstituted arylhydrazides.

Dithiocarbamates are of significant importance as pesticides, vulcanizing agents and pharmaceuticals. In search of efficient regioselective strategy, the various dithiocarbamate esters were synthesized by regioselective thiolation at endo-cyclic nitrogen of 2aminothiazole. The treatment of Boc-protected 2-aminothiazole with carbon disulphide and alkyl halide in the presence of potassium hydroxide in DMF afforded Boc-dithiocarbamate esters (3a-h). The removal of protecting group with TFA provided corresponding dithiocarbamate esters (4a-h). The formation of regioselective product was confirmed by spectral and molecular mechanical MM2 force field and PM3 approximation MOPAC energy minimization data. The strategy provides an important methodology for regioselective thiolation.

The electrochemical oxidation of dimethyl disulfide was investigated in acetonitrile and dichloromethane. The nature of the oxidation strongly depends on the nucleophilicity of the solvent. In acetonitrile a one-electron oxidation is observed and the consecutive species did not exhibit any reactivity towards aromatic compounds subject to electrophile substitution. On the contrary, the oxidation of dimethyl disulfide in methylene chloride afforded a two-electron process with the formation of a species consistent with CH 3 S +. Its reactivity towards phenols and aromatic ethers was confirmed and showed a selective monomethylsulfanylation in most of the cases.

Efficient synthetic methods were developed for the synthesis of mono xanthates, as well as mono dithiocarbamates of diamines and amino alcohols. This protocol utilizes the three component coupling of diols, diamines, and amino alcohols using alkyl bromides and carbon disulfide in the presence of a cesium base and tetrabutylammonium iodide (TBAI).

Efficient synthetic methods were developed for the synthesis of mono xanthates, as well as mono dithiocarbamates of diamines and amino alcohols. This protocol utilizes the three component coupling of diols, diamines, and amino alcohols using alkyl bromides and carbon disulfide in the presence of a cesium base and tetrabutylammonium iodide (TBAI).

The influence of experimental parameters on the yields and stereochemistry of the Wittig reaction was studied using the synthesis of stilbene initiated by different electrogenerated bases as a model reaction. Electrolyses were carried out in batch cells under different conditions, including constant potential or constant current with different electrode materials and using solvents of different polarity. It is shown that proper selection of experimental conditions in Wittig reactions allows a choice of stereoselectivity in the reactions and the optimization of yields.

The electrochemical oxidation of dimethyl disulfide was investigated in acetonitrile and dichloromethane. The nature of the oxidation strongly depends on the nucleophilicity of the solvent. In acetonitrile a one-electron oxidation is observed and the consecutive species did not exhibit any reactivity towards aromatic compounds subject to electrophile substitution. On the contrary, the oxidation of dimethyl disulfide in methylene chloride afforded a two-electron process with the formation of a species consistent with CH 3 S + . Its reactivity towards phenols and aromatic ethers was confirmed and showed a selective monomethylsulfanylation in most of the cases.

During the last few decades, Multi-Component Reactions (MCRs) have been studied as a facile route to assemble complex important structures in a small number of steps, while reducing production costs and environmental concerns. As a result, MCRs have attracted growing attention, leading to the development of new, highly selective methods for the synthesis of bioactive compounds such as natural products, drugs and agrochemicals [1]. Rhodanines, an important 5-membered class of heterocyclic compounds, represent a privileged scaffold in drug discovery. Rhodanine based compounds and their analogues have an inherent tendency towards pharmacological and therapeutic activities, such as antibacterial, antifungal, antiviral, antimalarial, antitumor, anti-in ammatory and cardiotonic activities [2]. 2-Thioxothiazolidin-4-ones are classically prepared [3] by the reaction of N-alkylthiocarbamate (formed in situ from an amine and carbon disul-

In order to show the advantages and limitations of organic electrosynthesis in the total synthesis of a natural product, one of the promising green chemistry techniques in organic chemistry, the synthesis of N-isobutyl-(2E,6Z)-dodecadienamide (3) was undertaken. Chemical and electrochemical routes that use the same intermediates were used to carry out the syntheses. Four reactions were compared from a green chemistry point of view in the synthesis of 3: (a) alcohol to aldehyde oxidation, (b) the Horner-Emmons reaction, (c) carboxylic acid amidation with triphenylphosphonium ions and (d) the Wittig reaction. All the electrolyses were carried out in non-divided cells at a constant current. The electrochemical method in the oxidation reaction of alcohols and the carboxylic acid amidation gave better yields (95% and 67%, respectively) than the corresponding chemical reactions. The Horner-Emmons reaction gave the same yields in both techniques (80-85%); however, the electrochemical method was more environmentally friendly, due to the fact that the base used was electrogenerated, avoiding corrosive and sensitive base manipulation. Finally, the electrochemical Wittig reaction was unsuccessful in the different experimental conditions attempted, and only the chemical method produced the target product. This study demonstrated that organic electrochemistry can be a reliable method for the synthesis of important intermediates, but not all electrochemical reactions can compete with the already well-established methods of organic chemistry.

A new family of N,N-disubstituted p-anisidine-based electroactive ligands bearing dipyridinylamino-(1), difuranylamino-(2) and dithiophenylamino-(3) binding sites has been prepared by reductive alkylation of anisidine. The electrochemical investigations, in 0.1 mol/dm-3 LiClO 4 acetonitrile solution, showed that upon the addition of metallic cations, the redox features of 1 underwent drastic changes due to the cation chelation. The chemosensor complexation with Ni(II), Zn(II), Cd(II) and Pb(II) led to large anodic shifts of the oxidation potential peaks up to 700 mV depending on the metal cation. A particularly high sensitivity toward nickel(II) with a higher selectivity to zinc(II) was observed. However, in the same conditions, thiophenyl-and furfuranyl-derivatives showed no sensitivity for any of the investigated cations. Moreover, UV-visible spectroscopy studies of 1 showed that the compound can act as a chromogenic guest-responsive and in presence of metallic cations, the absorption bands of compound 1 shifted due to a participation of the nitrogen lone pairs in the cation complexation. UV-visible spectroscopy did also allow to distinguish between the Ni(II) and Zn(II) complexes. Electrochemical and UV-visible spectroscopic investigations showed that the complexes have 1:2 stoichiometry [M(1) 2 ] 2+ (M: Zn, Ni, Cd and Pb).

A new family of N,N-disubstituted p-anisidine-based electroactive ligands bearing dipyridinylamino-(1), difuranylamino-(2) and dithiophenylamino-(3) binding sites has been prepared by reductive alkylation of anisidine. The electrochemical investigations, in 0.1 mol/dm-3 LiClO 4 acetonitrile solution, showed that upon the addition of metallic cations, the redox features of 1 underwent drastic changes due to the cation chelation. The chemosensor complexation with Ni(II), Zn(II), Cd(II) and Pb(II) led to large anodic shifts of the oxidation potential peaks up to 700 mV depending on the metal cation. A particularly high sensitivity toward nickel(II) with a higher selectivity to zinc(II) was observed. However, in the same conditions, thiophenyl-and furfuranyl-derivatives showed no sensitivity for any of the investigated cations. Moreover, UV-visible spectroscopy studies of 1 showed that the compound can act as a chromogenic guest-responsive and in presence of metallic cations, the absorption bands of compound 1 shifted due to a participation of the nitrogen lone pairs in the cation complexation. UV-visible spectroscopy did also allow to distinguish between the Ni(II) and Zn(II) complexes. Electrochemical and UV-visible spectroscopic investigations showed that the complexes have 1:2 stoichiometry [M(1) 2 ] 2+ (M: Zn, Ni, Cd and Pb).

Efficient synthetic methods were developed for the synthesis of mono xanthates, as well as mono dithiocarbamates of diamines and amino alcohols. This protocol utilizes the three component coupling of diols, diamines, and amino alcohols using alkyl bromides and carbon disulfide in the presence of a cesium base and tetrabutylammonium iodide (TBAI).

The use of electrogenerated acetonitrile anion allows the alkylation ofN-Boc-4-aminopyridine in very high yields, under mild conditions and without by-products. The high reactivity of this base is due to its large tetraethylammonium counterion, which leaves the acetonitrile anion “naked.” The deprotection of the obtained compounds led to high yields inN-alkylated 4-aminopyridines. Nonsymmetrically dialkylated 4-aminopyridines were obtained by subsequent reaction of monoalkylated ones witht-BuOK and alkyl halides, while symmetrically dialkylated 4-aminopyridines were obtained by direct reaction of 4-aminopyridine with an excess oft-BuOK and alkyl halides. Some mono- and dialkyl-4-aminopyridines were selected to evaluate antifungal and antiprotozoal activity; the dialkylated 4-aminopyridines3ac,3aeand3ffshowed antifungal towardsCryptococcus neoformans; whereas3cc,3eeand3ffshowed antiprotozoal activity towardsLeishmania infantumandPlasmodium falciparum.

The influence of experimental parameters on the yields and stereochemistry of the Wittig reaction was studied using the synthesis of stilbene initiated by different electrogenerated bases as a model reaction. Electrolyses were carried out in batch cells under different conditions, including constant potential or constant current with different electrode materials and using solvents of different polarity. It is shown that proper selection of experimental conditions in Wittig reactions allows a choice of stereoselectivity in the reactions and the optimization of yields.

Efficient synthetic methods were developed for the synthesis of mono xanthates, as well as mono dithiocarbamates of diamines and amino alcohols. This protocol utilizes the three component coupling of diols, diamines, and amino alcohols using alkyl bromides and carbon disulfide in the presence of a cesium base and tetrabutylammonium iodide (TBAI).

The synthesis of a new oxaaza macrocyclic ligand, L, derived from O(1),O(7)-bis(2-formylphenyl)-1,4,7-trioxaheptane and tren containing an amine terminal pendant arm, and its metal complexation with alkaline earth (M = Ca(2+), Sr(2+), Ba(2+)), transition (M = Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+)), post-transition (M = Pb(2+)), and Y(3+) and lanthanide (M = La(3+), Er(3+)) metal ions are reported. Crystal structures of [H(2)L](ClO(4))(2).3H(2)O, [PbL](ClO(4))(2), and [ZnLCl](ClO(4)).H(2)O are also reported. In the [PbL] complex, the metal ion is located inside the macrocyclic cavity coordinated by all N(4)O(3) donor atoms while, in the [ZnLCl] complex, the metal ion is encapsulated only by the nitrogen atoms present in the ligand. pi-pi interactions in the [H(2)L](ClO(4))(2).3H(2)O and [PbL](ClO(4))(2) structures are observed. Protonation and Zn(2+), Cd(2+), and Cu(2+) complexation were studied by means of potentiometric, UV-vis, and fluorescent emission measurements. The 10-fold f...

The 5(4H)-oxazolones I a-d with an slecrmwich aryl substituent an C-2 reaci with 4.5-dihydro-~-tria;r.olcs 2a-c to aKord the 4-[~4-1riazolyllmethyl]-S~4~ox~olones 321i as main reaction products and 2.5-diaryl-3-pyrrolecarbaldehydes 4rr-d and glycine diamides Sa -d as secondary reaction products. The 5(4H)oxazolones 1 e-h bearing an electron-~~ithilru~uinn substituent on thc aryl group on C-2 react with the 4,5dlihydro-~triazales 2c-e alfording thc 2-[(4-~rin;r.olyl)methyl~-5(2H)-oxaisolones 7a-e as main rcaciion products. Compounds 3 and I are produced by nucleophilic attack of the anion of 1 at the ex0 methylenc carbon. Aldehydes 4 are formed through rearrangement or an unstable cycloaddition product from I and 2. 1-Aryl-Cmethylene-5-amino-a-dihydrotriazoles have been extensively studied by our research group as substrates for both 1,3-dipolar cycloaddition reactions to the exocyclic double bond'-'' and for nucleophilic attack of amines, alkoxides, and thiolates'). In the case of l ,3-dipolar cycloadditions labile spiranic cycloadducts were gcnerally formed which underwent cleavage of the 1,-dihydrotriazole ring and rearranged to give substituted heterocycles. On the other 2a b d 1073 ~Triazoline, XXVIII'? -Reaktionen von l-Aryl-4,5-dibydro-.C methylen-5morpholino-plriazolen mit 2,4DiaryI-5(4H)-oxazole W O 5(4H)-Oxazolone 1 a-d mit clckwonenlirferndelm Rcsicn in 2-Position des Arylrests rcagieren mit 4,5-Dihydro-c-triazo~cii 2a -c m C[(4-Triazolyl)mcthyl)5-(4H~oxazoIoncn 3ai als Haupiund zu 2,5-Diaryl-3-pyrrolcarbaldehyden 4ad sowie Glycindiamiden 5a-d als Nebenprodukten. 5(4H)-Oxazolone mi! elcktronenzie/reden Substihenten (I e-b) lidern mit den 4.5-Dihydro-v-triazoten 2ce die 2-~(4-Triazolyl)methyl]-~?H)-ox~.~lonc 7a-e ats Hauptprodukte. Die Produkk 3 und 7 werdcn durch nucleophitcn Angriff dcs Anions von 1 am exo-Mcttiylcnkohlenstoff von 2 gebildct. Die Aldehyde 4 cntstchcn diircli Urnlagerung cines labilen Cycloaddukts aur I und 2. hand, nucleophiles reacted with the exocyclic double bond through an addition and/or addition-elimination process leading to substituted r-dihydrotriazoles andlor o-triamles, respectively. Recently, we have reported that reaction of these substrates with symmetrically and unsymmetrically substituted munchnones results in the formation of 2,5-disubstituted 3-pyrrolecarbaldehyde anils 'I. The results which were ob-4 , 5 a C, H, b C, H, -OCH, -4 c C6H4-CH3-4 d C, H, -OCH, -2

2-Oxoamides based on long chain β-amino acids were synthesized. 1-Benzyl substituted long chain amines, needed for such synthesis, were synthesized starting from Boc-phenylalaninol. The oxidative conversion of a phenyl group to a carboxyl group was used as the key transformation synthetic step. The compounds synthesized were studied for their activity against GIVA PLA 2 , and were proven to be weak inhibitors.

2-Oxoamides based on long chain β-amino acids were synthesized. 1-Benzyl substituted long chain amines, needed for such synthesis, were synthesized starting from Boc-phenylalaninol. The oxidative conversion of a phenyl group to a carboxyl group was used as the key transformation synthetic step. The compounds synthesized were studied for their activity against GIVA PLA 2 , and were proven to be weak inhibitors.

A new and mild method was developed for the chemoselective conversion of mono-, bis-and tris-aminosiloxanes into their corresponding mono-, bis-and tris-dithiocarbamates, using alkaline hydrides and carbon disulfide in THF. Enhanced scavenging capacity towards mercury ions was observed when these compounds were grafted on silica compared to amine-functionalized silicas or to commercial resins bearing dithiocarbamate moieties.

Intermolecular hydrogen bonds between 2,6-bis(acylamino)pyridines and dipyridin-2-ylamine as well as 4,4-dimethylpiperidine-2,6-dione are responsible for relatively strong interactions between these species. Association has been found to be significantly affected by the size of acyl substituent (chemical shift of the NH proton was used as the main probe in determination of the association constants). Calculations at the DFT level of theory are in line with the experimentally observed results. Calculated energies of the interactions between the complex congeners also show the size of the substituent to affect the association. Conformational changes in the dipyridin-2-ylamine molecule are shown to adapt a geometry suitable for formation of efficient hydrogen bonding.

An electrochemical deoxygenation reaction of aliphatic acetates has been developed, using electrogenerated organic amalgams (R 4 N-Hg). This methodology led us to obtain the deoxygenated product and the alcohol in a 1:1 ratio with total transformation of the starting compound. Examples using the acetates of sarsasapogenin, diosgenin, 16-dehydro-pregnanolone and argentatine A, show the applications and some limitations of this electrochemical reaction.

In order to show the advantages and limitations of organic electrosynthesis in the total synthesis of a natural product, one of the promising green chemistry techniques in organic chemistry, the synthesis of N-isobutyl-(2E,6Z)-dodecadienamide (3) was undertaken. Chemical and electrochemical routes that use the same intermediates were used to carry out the syntheses. Four reactions were compared from a green chemistry point of view in the synthesis of 3: (a) alcohol to aldehyde oxidation, (b) the Horner-Emmons reaction, (c) carboxylic acid amidation with triphenylphosphonium ions and (d) the Wittig reaction. All the electrolyses were carried out in non-divided cells at a constant current. The electrochemical method in the oxidation reaction of alcohols and the carboxylic acid amidation gave better yields (95% and 67%, respectively) than the corresponding chemical reactions. The Horner-Emmons reaction gave the same yields in both techniques (80-85%); however, the electrochemical method was more environmentally friendly, due to the fact that the base used was electrogenerated, avoiding corrosive and sensitive base manipulation. Finally, the electrochemical Wittig reaction was unsuccessful in the different experimental conditions attempted, and only the chemical method produced the target product. This study demonstrated that organic electrochemistry can be a reliable method for the synthesis of important intermediates, but not all electrochemical reactions can compete with the already well-established methods of organic chemistry.

cothodically initiated Michael addition of thiok to levoglucossn~ne using small currents produces the previously unknown &co add&Xl product in several im@ace& The n0rnul ayrhro irKDIner, identified as the kinetic pr0dIlct, ten& to be formed whm large currents are used. The slow, low curreot elsctroiysea promots equilibntti0n of the two forms 80 that eryrJn.0 can be converted to rhreo by the retro reaction sod readdition. Additknu to R-(+)-rpovabarrme and R-(-)-arvone are also repmted,

The electrochemically-induced addition of nitroalkenes to mono and dialdehydes as well as mono and diolefins was investigated. The reactivity was highly dependent on the solvent. Selectivity of addition has been made possible by controlling the charge injected upon electrolysis of a pure nitromethane solution in the presence of 1,3-or 1,4&nzenedicarboxaldehyde to direct the reaction toward the mono-or bis-(nitroalcohol).

Diethyl fumarate and related halogenated derivatives have been studied by cyclic voltammetry and electrolysis, on mercury and glassy carbon electrodes, in DMF + 0.1 mol L À1 TBAP and in acetonitrile + water (3:4) with 0.1 mol L À1 NaCl or 0.1 mol L À1 TEAP. For compounds with two reducible functionalities, the electron-deficient olefin and the C-X group, the grade of substitution on the halogenated carbon causes differences on the site involved in the first electron transfer thus determining the chemical reactivity. Enediester compounds with -CH 2 -groups insulating the gem-trihalide groups (-CX 3 , X ¼ Br and Cl) suffer reduction, and the C-X cleavage is the reaction of choice. The reaction pathway also depends on the nature of the electrode and significant positive potentials shifts for compounds with a gem-tribromide group are evident in the cyclic voltammogram on a mercury electrode, in relation to results on a glassy carbon electrode. The formation of easily reduced organomercurials is the main reason for this intense positive shift in the first electron transfer. On a vitreous carbon electrode, factors directly related to the strength of the C-X bond play a determinant role. Concerning electrolysis, the gem-tribromo derivative furnishes H 2 C@CBr 2 and ethyl hydrogenfumarate, through hydrolysis produced by initial cleavage of the C-Br. For the other polyfunctional compounds (-CHX 2 , -CH 2 X), the olefin is reduced first to yield dimers and/or hydrogenated products depending upon the reaction conditions. Quantum chemical calculations performed on the anion radical of these compounds yield spin densities located on the -CBr 3 /-CCl 3 group and on the enediester group for the -CCl 2 /-CBr 2 , -CH 2 Br/-CH 2 Cl derived compounds. Upon geometry optimisation, the C-Br bond in compounds containing -CBr 3 groups are longer, suggesting that this bond can easily be cleaved, yielding organomercurial compounds, in the case of the use of a mercury electrode or leading to bond cleavage, for inert electrodes. For the other substituents, the optimisation basically does not affect the geometry of the radical anion compared to the neutral substrate. These results have been confirmed by the calculated dissociation energy of the C-Br bond, which for the -CBr 3 group is approximately 100 kJ mol À1 as against 240 kJ mol À1 for the same bond in the -CH 2 Br group. The coherence between the experimental and calculated data reinforces the usefulness of these computational tools in rationalising the reactivity of electrogenerated species as well as in predicting the electrochemical reaction outcome.

cothodically initiated Michael addition of thiok to levoglucossn~ne using small currents produces the previously unknown &co add&Xl product in several im@ace& The n0rnul ayrhro irKDIner, identified as the kinetic pr0dIlct, ten& to be formed whm large currents are used. The slow, low curreot elsctroiysea promots equilibntti0n of the two forms 80 that eryrJn.0 can be converted to rhreo by the retro reaction sod readdition. Additknu to R-(+)-rpovabarrme and R-(-)-arvone are also repmted,

cothodically initiated Michael addition of thiok to levoglucossn~ne using small currents produces the previously unknown &co add&Xl product in several im@ace& The n0rnul ayrhro irKDIner, identified as the kinetic pr0dIlct, ten& to be formed whm large currents are used. The slow, low curreot elsctroiysea promots equilibntti0n of the two forms 80 that eryrJn.0 can be converted to rhreo by the retro reaction sod readdition. Additknu to R-(+)-rpovabarrme and R-(-)-arvone are also repmted,

A new family of N,N-disubstituted p-anisidine-based electroactive ligands bearing dipyridinylamino-(1), difuranylamino-(2) and dithiophenylamino-(3) binding sites has been prepared by reductive alkylation of anisidine. The electrochemical investigations, in 0.1 mol/dm -3 LiClO 4 acetonitrile solution, showed that upon the addition of metallic cations, the redox features of 1 underwent drastic changes due to the cation chelation. The chemosensor complexation with Ni(II), Zn(II), Cd(II) and Pb(II) led to large anodic shifts of the oxidation potential peaks up to 700 mV depending on the metal cation. A particularly high sensitivity toward nickel(II) with a higher selectivity to zinc(II) was observed. However, in the same conditions, thiophenyl-and furfuranyl-derivatives showed no sensitivity for any of the investigated cations. Moreover, UV-visible spectroscopy studies of 1 showed that the compound can act as a chromogenic guest-responsive and in presence of metallic cations, the absorption bands of compound 1 shifted due to a participation of the nitrogen lone pairs in the cation complexation. UV-visible spectroscopy did also allow to distinguish between the Ni(II) and Zn(II) complexes. Electrochemical and UV-visible spectroscopic investigations showed that the complexes have 1:2 stoichiometry [M(1) 2 ] 2+ (M: Zn, Ni, Cd and Pb).

Electrogenerated radical-anions of 1,4-bis(alkylsulfonyl)benzenes can undergo two modes of reversible bond cleavage (depending on the stability of the alkyl radical) to afford alkylated monosulfones and phenolates, the latter of which can be trapped as ethers by reaction with electrophiles (alkyl iodides). For starting materials with primary and secondary alkyl moieties, we propose that the initially formed radical-anions rearrange (via an electrophilic aryl radical) to give aryl sulfinate radical -anions which decompose to yield phenolates and alkyl radicals.

Intermolecular hydrogen bonds between 2,6-bis(acylamino)pyridines and dipyridin-2-ylamine as well as 4,4- dimethylpiperidine-2,6-dione are responsible for relatively strong interactions between these species. Association has been found to be significantly affected by the size of acyl substituent (chemical shift of the NH proton was used as the main probe in determination of the association constants). Calculations at the DFT level of theory are in line with the experimentally observed results. Calculated energies of the interactions between the complex congeners also show the size of the substituent to affect the association. Conformational changes in the dipyridin-2-ylamine molecule are shown to adapt a geometry suitable for formation of efficient hydrogen bonding.

Hindered rotation in alkyldithiocarbamates of the type RR NC( = S)SR [R, R , R = Me, Me, Et (1); PhCH 2 , Me, Et (2); PhCH 2 , H, Et (3); PhCH 2 , H, Me (4) and O(CH 2 CH 2 ) 2 , Et (5) has been investigated using variable-temperature 1 H NMR spectroscopy in CDCl 3 , C 6 D 6 , and DMSO-d 6 solutions. Rotational parameters were calculated by the coalescence temperature method. Nitrogen substituent effects on the free energy of activation and on the equilibrium constant of unsymmetrical conformers at room temperature are discussed.

Electrogenerated cyanomethyl anion promotes the reaction between primary or secondary amines, carbon disulfide and alkyl iodide to afford the corresponding organic dithiocarbamates in moderate yields. Secondary amines are converted to alkyl dithiocarbamates whereas primary amines give the alkyl-(1-imino-ethyl)-dithiocarbamic acid ester in two steps. The mechanism will be discussed.

The 07,;/CO2 system, originating from electrochemical one-electron reduction of dioxygen in dip&r aprotic solvents and in the presence of CO;?, converts primary and secondary alcohols bearing a leaving group at a or B position into the corresponding cyclic carbonates in high to excellent yields. Unsubstituted alcohols are also converted, but in unsatisfactory yields, into the corresponding alkyl ethyl carbonates after completion of the reaction by addition of Ett. Tertiary alcohols and phenols are stable to the reagent, thus allowing selcctivc carboxylation of polyhydroxy derivatives. CH-acid containing compounds undergo different reactions, if any, with the rcagcnt but in the casts under study the formation of carboxylation products has never been obscrvcd.

The known electrochemical synthesis of a; b-(E)-unsaturated esters (Horner-Emmons reaction) was modified in order to achieve the electrolysis in an undivided cell using magnesium as the sacrificial anode. The undivided cell procedure showed advantages over the traditional two-compartment cell methodology. The best yield using undivided cell methodology for the synthesis of aliphatic a; b-(E)-unsaturated esters was 85-86%, which is almost the yield obtained by means of the homogenous chemical reaction. This electrochemical methodology presented some limitations when aromatic aldehydes or base sensitive products were used.