Enediolates and dienediolates of carboxylic acids in synthesis. Synthesis of β,γ-epoxyacids from α-chloroketones

Abstract Lithium dienolates of saturated or α,β-unsaturated acids react with α-chloroketones provide a convenient method for preparation of highly sustituted β,γ-epoxyacids. These highly reactive compounds lead in most cases to variable ammounts of the corresponding β-lactones and allylic alcohols.

Dienediolates of unsaturated carboxylic acids in synthesis. Synthesis of cyclohexenones and polycyclic ketones by tandem Michael-Dieckmann decarboxylative annulation of unsaturated carboxylic acids.

Abstract Substituted 2-cyclohexenones 4 to 7 and hexaxydronaphthalenones and hexahydroindenones 13 to 18 are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of acyclic and alicyclic unsaturated carboxylic acids to the lithium salts of the same or other unsaturated carboxylic acids.

A brief structured view of green chemistry issues

ChemInform Abstract: Components of the Sex Pheromone of Chilo supressalis: Efficient Syntheses of (Z)-11-Hexadecenal and (Z)-13-Octadecenal.

Abstract (Z)-11-Hexedecenal 1a and (Z)-13-octadecenenal 2a, components of the sex attractant pheromone of Chilo supressalis, have been synthesized as their ethylene acetals 1b and 2b from cyclododecanone 3, through intermediacy of the C12 ω functionalized acetals 8 and 12.

Alkene epoxidations catalysed by Mo(VI) supported on Merrifield's polymer

High conversion and epoxide selectivity from alkenes is achieved with tert-butyl hydroperoxide and a polystyrene-grafted Mo(VI) catalyst, with no noticeable leaching of Mo from the support.

ChemInform Abstract: Conjugate Addition of Organolithium Reagents to α,β-Unsaturated Carboxylic Acids.

Abstract Conjugate addition of primary, secondary, tertiary alkyl and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.

Alkylation of lithium dienediolates of butenoic acids. Regioselectivity effects of structure and leaving group of the alkylating agent

Abstract Regioselectivity of alkylation of but-2-enoic acids 1 and 2 by alkyl halides strongly depends on the reactivity of the electrophile. High α selectivity results for saturated alkyl halides, whereas poor α-selectivity is obtained for highly reactive allyl and benzyl halides. For reactive alkylating halides selectivity is partly governed by the ion pairing aggregates of the dienediolates. Lithium bromide and the carboxylate generated in the ongoing reaction cause opposite effects on regioselectivity.

ChemInform Abstract: o-Nitroaryldioxolanes for Protection of Pheromones. Study of the Photodelivery of Carbonyl Compounds.

o-Nitrophenyldioxolanes 1 to 12 have been prepared and the rate of their photocleavage determined. Steric congestion in the molecule causes a decrease of the reaction rate. The decrease in the rate...

Synthesis of (Z)-5-Decenol and (Z)-5-Decenyl Acetate, Components of the Sex Pheromones of a Variety of Lepidoptera

Two simple Wittig procedures for the synthesis of (Z)-5-decenol and (Z)-5-decenyl acetate based on the monoacetylation or monobromination of 1,5-pentanediol were followed.

ChemInform Abstract: Trienediolates of Hexadienoic Acids in Synthesis. Synthesis of Retinoic and nor-Retinoic Acids.

Abstract Double deprotonation of either (E,E)-3-methyl-2,4-hexadienoic acid 2, or 4,6-dimethyldihydro-2-pyrone 3 generates apparently the same lithium trienediolate, which affords ω-hydroxy acids 9 on reaction with ketones 7. Hydroxy acids 9 are easily dehydrated to octatrienoic acids 5, which are structurally related to retinoic acid. Similarly, sorbic acid 1 leads to nor-retinoic acid analogs 6.

O-Nitroaryldioxolanes for Protection of Pheromones. Study of the Photodelivery of Carbonyl Compounds

o-Nitrophenyldioxolanes 1 to 12 have been prepared and the rate of their photocleavage determined. Steric congestion in the molecule causes a decrease of the reaction rate. The decrease in the rate is especially important in the presence of a nitro group in a second phenyl ring.

ChemInform Abstract: Addition of Organolithium Reagents to Cinnamic Acids.

Abstract Reaction of tert -butyllithium with p - and m -substituted cinnamic acids at low temperature affords mixtures of 1,4- and 1,3-addition products, whose composition depend on the nature of the substituents. Electron-donating and electron-withdrawing groups favour 1,4- and 1,3-additions, respectively. Linear correlations are obtained with electronic effect and with radical substituent constants.

High atomic yield bromine-less benzylic bromination

A two-phase mixture (sodium bromide, aqueous hydrogen peroxide/carbon tetrachloride or chloroform) under visible light provides a simple and convenient system for benzylic bromination of toluenes. A high atomic yield for bromine atoms is attained. Substitution of the chlorinated solvents by other more environmentally benign organic solvents has been attempted and good results are obtained for methyl pivalate.

A Green Look at the Aldol Reaction

Aldol reactions have been and are widely applied for the preparation of β-hydroxy aldehydes, β-hydroxy ketones or α,β-unsaturated aldehydes or ketones through addition or addition-elimination reactions of aldehydes and ketones. The study of the aldol reaction from the point of view of its greenness must have in mind first of all that a general synthetic method must be based on complete and efficient conversions of well defined selectivity and that greenness is more a term for comparison than an absolute kind of qualification. This comparison, when referred to the aldol reaction, applies here to the diverse modifications of the reaction. Thus, the original poorly selective, but highly atom e…

Iodine oxidative coupling of diene and triene-diolates of unsaturated carboxylic acids.

Abstract Oxidative Coupling of the dianions of unsaturated carboxylic acids 1 , and 4 with iodine, which provides a convenient and facile preparation of γ,γ and e,e-dicarboxylic acids 2 and 5, apparently occurs through SET substitution of intermediate iodo-carboxylates.

Polyenolates of unsaturated carboxylic acids in synthesis. A straightforward synthesis of retinoic acids.

Abstract Retinoic acids are prepared in a two step procedure by addition of lithium trienediolates of sorbic acid and 3-methyl-sorbic acid to β-ionone.

Dienediolates of unsaturated carboxylic acids in synthesis. Aldehydes and ketones from alkyl halides, by ozonolysis of β,γ-unsaturated α-alkyl carboxylic acids. The role of a tertiary amine in the cleavage of ozonides

Abstract A convenient two-step procedure for a two carbon homologative conversion of alkyl halides into aldehydes and methyl ketones by α-alkylation of unsaturated carboxylic acids, followed by ozonolysis is developed and applied to the synthesis of ω-chloro aldehydes. Triethylamine is superior to dimethyl sulfide or triphenylphosphine for cleavage of the ozonides, except when aldol condensation side reactions require use of protic solvents and iodide salts. Cleavage of the ozonides by triethylamine is shown to occur mainly through a reductive process.

ChemInform Abstract: Synthesis of Dienedioic and Tetraenedioic Acids by Oxidative Coupling of Unsaturated Carboxylic Acid Dienediolates by 1,2-Diiodoethane.

Abstract Acyclic and cyclic unsaturated carboxylic acids 1 to 4 are most easily converted to unsaturated dicarboxylic acids 5 to 8 by oxidative coupling of their diene- or triene-diolates by 1,2-diiodoethane. This procedure improves formerly reported oxidations by iodine or silver salts.

Lithium enediolates and dienediolates of carboxylic acids in synthesis: Alkylation with secondary halides

Abstract High yields in the alkylation of dianions of α,β-unsaturated carboxylic acids with secondary halides can be obtained despite elimination reactions occurring. α-Regioselectivity for the alkylation of but-2-enoic acids ( 1–4 ) is seldom obtained. Although double bond stereoselectivity is higher than 99% for γ-alkylated products, stereoselectivity is rather poor for most of the α-alkylated products.

Addition of organolithium reagents to cinnamic acids

Abstract Reaction of tert -butyllithium with p - and m -substituted cinnamic acids at low temperature affords mixtures of 1,4- and 1,3-addition products, whose composition depend on the nature of the substituents. Electron-donating and electron-withdrawing groups favour 1,4- and 1,3-additions, respectively. Linear correlations are obtained with electronic effect and with radical substituent constants.

ChemInform Abstract: Trienediolates of Hexadienoic Acids in Synthesis. Addition to Unsaturated Ketones. A Convergent Approach to the Synthesis of Retinoic Acids.

Abstract The regioselectivity of the addition of the lithium trienediolates generated from hexa-2,4dienoic acids 1 and 2 or the dihydropyran-2ones 4 and 5 to unsaturated ketones 6 is studied. Equilibration conditions favour reaction of the trienediolates through their ω carbon, and the ketones according to 1,2- and 1,4-additions. β-Ionone 6a and the aryl-butenone 6b lead to the 1,2-ω-adducts 8 , which undergo a facile acid catalyzed dehydration to retmoic acids 11 . On reaction with the unsaturated ketone 6b or with the aryl ketones 21 , the trimethyldihydropyran-2one S leads to γ-adducts derived from deprotonation of the chain methyl mbstituent along with the 1,4-ω-adducts.

Components of the Sex Pheromone of Chilo Supressalis: Efficient Syntheses of (Z)-11-Hexadecenal and (Z)-13-Octadecenal

Abstract (Z)-11-Hexedecenal 1a and (Z)-13-octadecenenal 2a, components of the sex attractant pheromone of Chilo supressalis, have been synthesized as their ethylene acetals 1b and 2b from cyclododecanone 3, through intermediacy of the C12 ω functionalized acetals 8 and 12.

ChemInform Abstract: Alkylation of Lithium Dienediolates of Butenoic Acids. Regioselectivity Effects of Structure and Leaving Group of the Alkylating Agent.

Abstract Regioselectivity of alkylation of but-2-enoic acids 1 and 2 by alkyl halides strongly depends on the reactivity of the electrophile. High α selectivity results for saturated alkyl halides, whereas poor α-selectivity is obtained for highly reactive allyl and benzyl halides. For reactive alkylating halides selectivity is partly governed by the ion pairing aggregates of the dienediolates. Lithium bromide and the carboxylate generated in the ongoing reaction cause opposite effects on regioselectivity.

Trienediolates of hexadienoic acids in synthesis. synthesis of retinoic and nor-retinoic acids.

Abstract Double deprotonation of either (E,E)-3-methyl-2,4-hexadienoic acid 2, or 4,6-dimethyldihydro-2-pyrone 3 generates apparently the same lithium trienediolate, which affords ω-hydroxy acids 9 on reaction with ketones 7. Hydroxy acids 9 are easily dehydrated to octatrienoic acids 5, which are structurally related to retinoic acid. Similarly, sorbic acid 1 leads to nor-retinoic acid analogs 6.

ChemInform Abstract: Iodine Oxidative Coupling of Diene- and Triene-Diolates of Unsaturated Carboxylic Acids.

Abstract Oxidative Coupling of the dianions of unsaturated carboxylic acids 1 , and 4 with iodine, which provides a convenient and facile preparation of γ,γ and e,e-dicarboxylic acids 2 and 5, apparently occurs through SET substitution of intermediate iodo-carboxylates.

ChemInform Abstract: Enediolates and Dienediolates of Carboxylic Acids in Synthesis. Synthesis of β,γ-Epoxyacids from α-Chloroketones.

Abstract Lithium dienolates of saturated or α,β-unsaturated acids react with α-chloroketones provide a convenient method for preparation of highly sustituted β,γ-epoxyacids. These highly reactive compounds lead in most cases to variable ammounts of the corresponding β-lactones and allylic alcohols.

Trienediolates of hexadienoic acids in synthesis. Addition to unsaturated ketones. A convergent approach to the synthesis of retinoic acids

Abstract The regioselectivity of the addition of the lithium trienediolates generated from hexa-2,4dienoic acids 1 and 2 or the dihydropyran-2ones 4 and 5 to unsaturated ketones 6 is studied. Equilibration conditions favour reaction of the trienediolates through their ω carbon, and the ketones according to 1,2- and 1,4-additions. β-Ionone 6a and the aryl-butenone 6b lead to the 1,2-ω-adducts 8 , which undergo a facile acid catalyzed dehydration to retmoic acids 11 . On reaction with the unsaturated ketone 6b or with the aryl ketones 21 , the trimethyldihydropyran-2one S leads to γ-adducts derived from deprotonation of the chain methyl mbstituent along with the 1,4-ω-adducts.

ChemInform Abstract: Dienediolates of Unsaturated Carboxylic Acids in Synthesis. Synthesis of Cyclohexenones and Polycyclic Ketones by Tandem Michael-Dieckmann Decarboxylative Annulation of Unsaturated Carboxylic Acids.

Abstract Substituted 2-cyclohexenones 4 to 7 and hexaxydronaphthalenones and hexahydroindenones 13 to 18 are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of acyclic and alicyclic unsaturated carboxylic acids to the lithium salts of the same or other unsaturated carboxylic acids.

On the mechanism of the addition of organolithium reagents to cinnamic acids

Abstract The regioselectivity of the addition of tert-butyllithium to cinnamic acid is subject to reaction conditions and to substituent electronic effects. Significant effects are observed in the presence of several additives including a radical trap such as α-methylstyrene. Competition experiments by addition of the organolithium reagent to mixtures of substituted cinnamic acids show that the relative rates of both conversion of the starting acids and formation of the 1,3-adducts are subject to electronic effects, whereas rates for 1,4-addition are independent of the substituents. These features are in agreement with a polar addition mechanism, but a fast SET equilibrium followed by slow …

Conjugate addition of organolithium reagents to α,β-unsaturated carboxylic acids

Abstract Conjugate addition of primary, secondary, tertiary alkyl and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.

Dienediolates of Unsaturated Carboxylic Acids in Synthesis. Tandem Michael Diechmann Synthesis of Substituted 2-Cyclohexenones

Abstract 3,5-Disubstituted 2-Cyclohexenones are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of dimethylacrylic and β-methylcinnamic acids to lithium carboxylates of unsaturated carboxylic acids.

Dianions of Unsaturated Carboxylic Acids in Synthesis. Synthesis of Juvocimene I

Abstract Juvocimene I is prepared by a non ambiguous synthesis based on the regioselective alkylation of 4-methylhexa-2,4-dienoic acid, and Wittig olefination of the aldehyde corresponding to the alkylated acid.

New simple convergent synthetic method for benzyl aryl ether dendritic structures

Abstract Phenolic benzyl aryl ether based dendrons with an ester periphery are easily prepared by convergent strategy through hydroxy substituted methyl benzoates and easily attainable benzoyl protected 3,5-bis(bromomethyl)phenol. The dendrons obtained can afford dendronized styrenes.

ChemInform Abstract: New Conditions for the Generation of Dianions of Carboxylic Acids.

Abstract Lithium carboxylic acid enediolates are generated efficiently using lithium amides prepared from thienyllithium or butyllithium and either diethylamine, piperazine, N,N′-dibenzylethylenediamine, N-benzylpiperazine or 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, even in catalytic amounts.

Chemistry and environment (CE) in Spain.

New conditions for the generation of dianions of carboxylic acids

Abstract Lithium carboxylic acid enediolates are generated efficiently using lithium amides prepared from thienyllithium or butyllithium and either diethylamine, piperazine, N,N′-dibenzylethylenediamine, N-benzylpiperazine or 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, even in catalytic amounts.

Polyenolates of Unsaturated Carboxylic Acids in Synthesis. Synthesis of Unsaturated α-Amino Acids and β-Hydrazing Acids

Abstract Regioselective reaction of lithium diene-and triene-diolates 1 and 2 with O-diphenylphosphinyl hydroxylamine affords unsaturated α-amino acids 3 and 4. Addition to DEAD leads selectively to γ-hydrazino unsaturated acids 5 and 6.

Química Sostenible: Naturaleza, fines y ámbito

Green and Sustainable C hemistry: Nature, Aims and Scope Green Chemistry entails a philosophy which is summarized in the twelve principles enunciated by Anastas and Warner, and whose aim is an industrial chemical process based on clean and safe reactions. This philosophy applies as well to other industries and activities which are based on chemical conversions, or on use of chemicals. Study of the industrial chemical process allows the visualization of convenient strategies for its greening, which are to be accomplished by related research or development fields, such as use of renewable source materials, substitution of traditional organic solvents, use of catalytic and biocatalytic procedu…

ChemInform Abstract: Lithium Enediolates and Dienediolates of Carboxylic Acids in Synthesis: Alkylation with Secondary Halides.

Abstract High yields in the alkylation of dianions of α,β-unsaturated carboxylic acids with secondary halides can be obtained despite elimination reactions occurring. α-Regioselectivity for the alkylation of but-2-enoic acids ( 1–4 ) is seldom obtained. Although double bond stereoselectivity is higher than 99% for γ-alkylated products, stereoselectivity is rather poor for most of the α-alkylated products.

Synthesis of Dienedioic and Tetraenedioic Acids by Oxidative Coupling of Unsaturated Carboxylic Acid Dienediolates by 1,2-Diiodoethane

Abstract Acyclic and cyclic unsaturated carboxylic acids 1 to 4 are most easily converted to unsaturated dicarboxylic acids 5 to 8 by oxidative coupling of their diene- or triene-diolates by 1,2-diiodoethane. This procedure improves formerly reported oxidations by iodine or silver salts.

Synthesis of (Z)-5-Decenol and (Z)-5-Decenyl Acetate, Components of the Sex Pheromones of a Variety of Lepidoptera.

Two simple Wittig procedures for the synthesis of (Z)-5-decenol and (Z)-5-decenyl acetate based on the monoacetylation or monobromination of 1,5-pentanediol were followed.

13C NMR studies of dianions of unsaturated carboxylic acids

Abstract 13C NMR Spectra of the dianions Li2-n resulting from double deprotonation of unsaturated carboxylic acids 1 to 6 by lithium dialkylamides, are examined. Higher field resonance for C2 than for C4 atoms are observed, which reveal higher elctron density at C2 than at C4, in agreement with the kinetic α-regioselectivity exhibited by these dianions on reaction with electrophiles.

Silver ion oxidative coupling of diene and triene-diolates of unsaturated carboxylic acids. A facile synthesis of octa- and dodeca-dienedioic acids

Abstract Polyunsaterated dicarboxylic acids 3 and 5 are very easily prepared by oxidative coupling of lithium diene- and triene-diolates 1 and 2 with silver nitrate.

ChemInform Abstract: Dianions of Unsaturated Carboxylic Acids in Synthesis. Synthesis of Juvocimene I.

Abstract Juvocimene I is prepared by a non ambiguous synthesis based on the regioselective alkylation of 4-methylhexa-2,4-dienoic acid, and Wittig olefination of the aldehyde corresponding to the alkylated acid.