Search

Reaction of selenazadienes with α-haloketones gave 5-acyl-2-amino-1,3-selenazoles in high yields.

A new biocatalytic route for the synthesis of both enantiomers of Timolol (1) is described. Starting from 3,4-dichloro1,2,5-thiadiazole (2), (R)- and (S)-Timolol (87% ee) were obtained in 35% and 30% overall yield, respectively. Asymmetric reduction of the intermediate haloketone 5 with baker's yeast afforded the corresponding halohydrin 6 in the optically active form (87% ee), which gave the R enantiomer (distomer) of Timolol. The S enantiomer (eutomer) was obtained via inversion of configuration of the halohydrin following the Mitsunobu procedure.

On controlled heating to 100 o C, 3-chloro-3-cyclobutene-1,2-diones (5a) reacted with 1,1'-bi-1-cyclohexenyl (6) and 1,1'-bi-1-cyclopentenyl (13) to give the dicycloalkano-annulated dihydrobenzocyclobutenediones 7 and 16, respectively. Treatment of carbon tetrachloride solutions of 7 and 16 with bromine at reflux temperature afforded the corresponding benzocyclobutenediones 9 and 17. Surprisingly, the reaction of 5a with 1,1'-bi-1-cycloheptenyl (14) and 1,1'-bi-1-cyclooctenyl (15) gave directly the benzocyclobutenediones 20 and 21. The hitherto unknown 3-bromo-3-cyclobutene-1,2-dione (5c) was prepared by treatment of 3-hydroxy-3-cyclobutene-1,2-dione (5b) with oxalic dibromide in 76% yield. Its reaction with the dienes 6, 13, 14 has been investigated

A convenient synthesis of monoacetals of α-diones, i. e. α-keto acetals, was developed by silver ion induced alcoholysis of regiospecifically formed α-bromo-α-chloro ketones. Similarly, the corresponding α,α-dial- koxy ketimines were synthesized from silver ion induced alcoholysis of α-bromo-α-chloro ketimines. Both methods provide an easy access to protected forms of α-diones, useful as building blocks in organic chemistry

4,4-Dialkyltetrahydro-3-furanones were prepared by ring closure of 3,3-dialkyl-1-bromo-4-chloro-2-butanones under the influence of sodium alkoxides and subsequent aqueous hydrolysis of the resulting 3,3-dialkoxy-4,4-dialkyltetrahydrofurans

The cyclization reaction of diallyldibutyltin and α-or y-halo ketones, especially chloro-substituted ketones, effectively proceeds in the presence of a catalytic amount of tetraethylammonium chloride, producing the corresponding 2-allyloxiranes or 2-allyltetrahydrofurans in high yield, respectively. β-Chloro ketones give the corresponding allyl alcohols

(E)-9-Chloro-4-methyl-8-oxo-4-nonenoic acid, a useful intermediate in the synthesis of the potent antigestational agent ORF-13811 (a 3,8-dioxabicyclo[3.2.1]octane derivative), is efficiently prepared from 4-chloro-2-methyl-2-butene by using the ortho ester Claisen rearrangement

A new synthesis of some 2-substituted 3-perfluoroalkyl 1,3-dicarbonyl compounds by the reaction of stabilized phosphonium ylides with perfluoronitriles is reported. The 19 F-NMR data of these compounds are discussed

Various types of α-bromo aldehyde and ketone derivatives of nitroxyl radicals can be prepared in a selective bromination reaction with pyrrolidone hydrotribromide in the presence of a double bond. The saturated α-bromo aldehydes are dehydrobrominated with 1,8-diazabicyclo [5,4,0]undec-7-ene

alpha-Amino keto acetals (beta,beta-dialkoxyamines) are synthesized in a regiospecific way by the reaction of alpha-bromo-alpha-chloro ketimines with sodium borohydride in methanol. As alpha-bromo-alpha-chloro ketimines are formed regiospecifically from alpha,alpha-dihalogenated ketones, derived from the corresponding ketones, this methodology entails a regiospecific synthesis of alpha-amino keto acetals from ketones.

The title compounds, 2-aryl-3-iodo-4H-1-benzopyrans and 2-alkyl- or 2-aryl-3-iodo-4H-1-benzothiopyrans, were prepared by reaction of the corresponding heterocyclic derivatives with the iodine-cerium(IV) ammonium nitrate system under mild conditions. The scope and proposed mechanism of the reaction were also demonstrated

Aromatic nucleophilic N-S and N-O exchange reactions of N,N-dimethyl-2,4-bis(trifluoroacetyl)-1-naphthylamine (1) with thiophenols and phenols gave the corresponding 2,4-bis(trifluoroacetyl)-1-(arylthio) naphthalenes 2 and -1-(4-methoxyphenoxy) naphthalene (5) in moderate to excellent yields. Acid-catalyzed cyclization reactions of 2 and 5 afforded fluorine-containing 7H-benzo[c]thioxanthenes 3,4 and 7H-benzo[c]xanthenes 6,7, respectively, in high yields

N-(4,4,4-Trifluoro-3-oxo-1-butenyl) amino acid esters, α-aminoacetophenones and aminoacetonitriles 3 and 4 are easily obtained in excellent yields by 0-N exchange reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones 1 and 2 with some amino acid esters, α-aminoacetophenone and aminoacetonitrile. Cyclodehydration of some resultant products into fluorine-containing pyrroles is also described

The hydrolysis of 6,6-dialkylthio- and 6-alkyl(or aryl)thio-1,1,1-trifluoro-3,5-hexadien-2-ones 2, 5 with potassium hydroxide in ethanol proceeds quite easily to give the corresponding 2,4-pentadienoic acids 3, 6, respectively, in excellent yields. Bistrifluoroacetyl compounds 8, 10a, b give corresponding monocarboxylic acids 6a, 3a, b in high yields, with accompanied monodecarboxylation

The reaction of ethyl α-chloro- or α-bromocarboxylates 1 with in situ generated dihalomethyllithium (1:2 molar ratio) at −78 o C leads, after hydrolysis, to the corresponding α,α,α'-trihalo ketones 4

Irradiation of 3-bromocamphor in MeOH induced a remarkable and efficient dimerization to provide three α-camphoryl-camphors [3 (exolendo), 4 (endolendo) and 5 (exolexo)].

Tributyltin hydride-mediated radical cyclization of N-[2,2-bis(phenylthio)ethenyl]-α-bromoalkanamides bearing (S)-1-phenylethyl group on the nitrogen atom gave (4S)-4-bis(phenylthio)-methyl-2-azetidinones as major products. The method was applied to the synthesis of a chiral precursor of carbapenem antibiotic (+)-PS-5.

Methyl 4-oxoalkanoates have been obtained in good yields by treatment of 1,2-dichloro-2-alken-4-ones with sodium carbonate in methanol fol- lowed by acid-catalyzed hydrolysis of the intermediate 5-alkyl-2,2- dimethoxy-2,3-dihydrofurans

A three step synthesis of bis[1H-imidazol-4(5)-yl]ethane (4a) and the trityl derivatives 4b-e, involving cyclization of α,ω-dichloroalkane-diones 3 with formamidine acetate in liquid ammonia as a solvent, is reported.

The Friedel-Crafts condensation of acetyl chloride and vinylidene chloride (1,1-dichloroethylene) in dichloromethane solution gives 4,4,4-trichloro-2-butanone (2), which is smoothly dehydrohalogenated with triethylamine to produce 4,4-dichloro-3-buten-2-one (1) in excellent yield

Symmetrically substituted β-amino α,β-unsaturated ketones react with sulfamide giving 2H-1,2,6-thiadiazine 1,1-dioxides in excellent yields. Unsymmetrically substituted β-amino and β-chloro α,β-unsaturated ketones also react with benzylsulfamide to yield thiadiazine derivatives in good chemical yields and excellent regioselectivity

3-Chloro-2-alkanones were regiospecifically synthesized from methyl 2-alkyl-3-oxobutanoates by chlorination to afford methyl 2-alkyl-2-chloro-3-oxobutanoates followed by demethoxycarbonylation in acid medium

Reaction of acetylpyrroles with benzyltrimethylammonium dichloroiodate in tetrahydrofuran solution leads to the corresponding α-chloro derivatives with high selectivity and good yields

1-Amino-2-thioxo-4-imidazolidinones 1 react with phenacyl bromides to yield 3-alkoxycarbonylmethyl-5-aryl-2-iminio-3.6-dihydro-2H-1,3,4-thiadiazine salts. Compounds 1 also react with aryl isothiocyanates to give N-aryl-N'-(3-aryl/alkyl-4-oxo-2-thioxoimidazolidinyl)thioureas, which by the action of amines undergo a ring-closure/ring-opening reaction to give 4-aryl-1-aryl/alkylaminocarbonylmethyl-3-sulfido-5-thioxo-3,4-dihydro-1H-1,2,4-triazole derivatives

Preparation d'halogenocetones, cetoethers, cetosulfines par reaction des iodures d'alkyle-manganese avec des chlorures d'acyle ou avec des anhydrides

A method to protect the amino group of the amino acids using diethyl (ethoxymethylene) malonate is described. The resulting derivatives are easily esterified with different alkylation agents. Elimination of the N-protecting group with bromine in chloroform affords the hydrobromides of the amino acid esters

Synthese par hydrolyse acide d'aryl-2 bromo-2 alkyl dioxolanne-1,3dicarboxylate-4,5 de dimethyle

Synthese des composes du titre par reaction d'isocyanates aryliques avec des bromures d'amino-3 benzylthio-2 phenyl-4 thiazolium-3, ou par reaction de bromo-2 acetophenones avec des arylidenamino-3 phenyl-4 thiazoline-4thiones-2

Synthese de ces halogenocetones par reaction du chlorure de dichloroacetyle avec des halogenures d'alkyl-magnesium

Synthese par action du bromure de mercapto-2 benzyl triphenyl phosphonium respectivement sur des chlorures d'acyle et sur des α-halogenocetones

Synthese par condensation de salicylaldehydes et du chloro-4 acetylacetate d'ethyle en presence de KF dans le methanol ou l'ethanol ou en presence de K 2 CO 3 dans l'acetone

Synthese de iodo-2 alcanones et alcanals par reaction des aldehydes et cetones avec HgCl 2 -I 2

Synthese du compose du titre par addition de Diels Alder de l'acroleine avec le tetrachlorocyclopentadiene, avec comme etape cle, la photooxygenation du tetrachloro-1,4,5,6 morpholinomethylene-2norbornane intermediaire

Alkylation en 1' de la thiamine ou de son derive [hydroxy-1' ethyl]-2 par des halogenures d'alkyle, la bromoacetone ou le bromacetate de methyle

Synthese par reaction de (methoxy-4 trifluoro-1,1,1) pentene-3one-2 avec des derives du propene-2ol-1

A partir de R-1 formyl-3 1H-pyridinethiones-2, synthese de bromures d'aroyl-1 R-7 thieno [2,3-b] pyridiniums (A) (R=isopropyl ou phenyl) par action de bromo-2 acetophenones ou par action d'acetophenones suivie de bromation; traitement thermique des composes A avec R=isopropyl conduisant aux aroyl-2 thieno [2,3-b] pyridines

Synthese a partir de la reaction du (benzoylmethylenetriphenyl) phosphorane avec le chlorure de trifluoroacetyle, suivie de la pyrolyse (200°-220°C) des (α-aroyl α-polyfluoroacetyl P,P,P-triphenyl) phosphoranes formes

Synthese par reaction d'enolates de lithium de cetones ou d'aldehydes avec des α-chloro-cetones et -aldehydes