Condensation of 5-bromo-, 3-bromo-, and 3-iodoacenaphthenequinones with 3-hydroxythionaphthene and its derivatives

The oxidation of 3-bromo-and 3-iodoacenaphthene has given 3-bromo-and 3-iodoacenaphthenequinones. The condensation of 5-bromo-, 3-bromo-, and 3-iodoacenaphthenequinones with 3-hydroxythionaphthene and its derivatives has yielded indigoid dyes, and the main light absorption maxima of these dyes have been determined.     

Synthesis of 3-aminomethyl-2-aryl- 8-bromo-6-chlorochromones

[reaction: see text] An efficient synthetic route to Cbz-protected 3-aminomethyl-2-aryl-8-bromo-6-chlorochromones has been developed. 3-Aryl-1-(3-bromo-5-chloro-2-hydroxyphenyl)-2-propen-1-one or 2-aryl-8-bromo-6-chlorochroman-4-one could be reacted under Mannich conditions yielding 2-aryl-8-bromo-6-chloro-3-methylenechroman-4-one, which was further converted to the target compound via an aza-Michael reaction followed by an SeO(2) oxidation. This procedure represents a new method to introduce a primary aminomethyl group at the 3-position of a 2-arylchromone scaffold. The Cbz-protected 3-aminomethyl-2-aryl-8-bromo-6-chlorochromones can, e.g., be used in the synthesis of chromone-based beta-turn peptidomimetics.     

Preparation of 3-bromo-2-methylfuran and 4-bromo-2-methylfuran

4-endo-5-exo-Dibromo-3-methyl-3,6-endo-oxyperhydrophthalic anhydride 3b and 4-exo-5-endo-dibro-mo-3-methyl-3,6-endo-oxyperhydrophtbalic anhydride 3c were isolated from the bromo-adducts of 3-methyl-3,6-endo-oxy-1,2,3,6-tetrahydrophthalic anhydride 2. When 3b or 3c was heated in quinoline, only 3-bromo-2-methylfuran 4 was obtained from 3b and only 4-bromo-2-methylfuran 5 from 3c.     

Silica gel-promoted convenient synthesis of 2-bromo-3-hydroxybenzoate derivatives

A convenient silica gel-promoted synthesis of 2-bromo-3-hydroxybenzoate derivatives has been developed via the Diels–Alder reaction of furans with methyl 3-bromopropiolate, followed by a ring-opening aromatization. In addition, 2-bromo-3-methoxybenzoate, derived from 2-bromo-3-hydroxybenzoate with iodomethane, was found to be a good substrate for Pd-catalyzed cross-coupling reactions, despite its sterically hindered structure.     

Unforeseen formation of 2-bromo-3-hydroxybenzaldehyde by bromination of 3-hydroxybenzaldehyde

Contrary to literature reports, bromination of 3-hydroxybenzaldehyde can afford both 2-bromo-5-hydroxybenzaldehyde and 2-bromo-3-hydroxybenzaldehyde, but 4-bromo-3-hydroxybenzaldehyde was not detected. 2-Bromo-3-hydroxybenzaldehyde was converted into 2-(benzyloxy)-1-bromo-5-methoxy-7-methylnaphthalene. X-ray crystallographic analysis supports the identity of 2-bromo-3-hydroxybenzaldehyde.     

On the grignard reaction of 2-bromo-3-iodo- and 3-bromo-2-chlorothiophene

2-Bromo-3-iodo- and 3-bromo-2-chlorothiophene react with magnesium in the presence of 1,2-dibrornoethane to give 2-halo-3-thiophene magnesium halide which opens a useful route to 2,3-disubstituted thiophenes having an electron-withdrawing group in the 3-position.     

Regioselective synthesis of ω-bromo-3-ketosulfones, ω-bromo-3-ketonitriles and 2-(ω-bromoalkyl)benzofurans based on a ‘ring-closing/ring-opening’ strategy

ω-Bromo-3-ketosulfones, ω-bromo-3-ketonitriles and various functionalized 2-(ω-bromoalkyl)benzofurans were chemo- and regioselectively prepared by application of a ‘ring-closing/ring-opening’ strategy. The cyclization of 3-ketosulfone and 3-ketonitrile dianions with 1-bromo-2-chloroethane or 1,4-dibromobut-2-ene afforded functionalized 2-alkylidenetetrahydrofurans which were subsequently cleaved by reaction with boron tribromide or boron trichloride to give the final products.     

Brom-hydroxychalkone

Zusammenfassung Eine Anzahl von Bromhydroxychalkonen sind durch Kondensation verschiedener aromatischer Aldehyde mit 2-Hydroxy-3-brom-, 4-Hydroxy-5-brom-und 2-Hydroxy-5-brom-acetophenon hergestellt worden. Die UV-Spektren dieser Chalkone wurden aufgenommen.

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A number of bromohydroxychalkones have been prepared by condensation of various aromatic aldehydes with 2-hydroxy-3-bromo-, 4-hydroxy-5-bromo-and 2-hydroxy-5-bromoacetophenone. The ultraviolet absorption spectra of these chalcones have been recorded.

     

Reaction of trihalo(phenylenedioxy)phosphoranes with acetylenes: X. specific features of the reactions of substituted 2,2,2-trichloro-1,3,2λ5-benzodioxaphospholes with 3-chloro(bromo, iodo)propynes

It was shown for the first time that 3-chloro-, 3-bromo-, and 3-iodopropynes can react with 2,2,2-trichloro-, 2,2,2-trichloro-5-methyl-, and 5,6-dibromo-2,2,2-trichloro-1,3,2λ⁵-benzodioxaphospholes to give derivatives of 4-(halomethyl)-2-chloro-2H-1,2λ⁵-benzoxaphosphinin-2-ones. The reaction involves nonselective chlorination of the phenylene substituent in different positions, and the resulting isomer ratio is temperature-dependent. In the reactions of 3-bromo-and 3-iodopropynes with 2,2,2-trichloro-1,3,2λ⁵-benzo-dioxaphosphole, a side process takes place, viz. nucleophilic substitution of bromine and iodine with chlorine. The structure of some of the prepared 4-(chloromethyl)-1,2-benzoxaphosphinines was studied by means of X-ray diffraction.     

Unusual thermal isomerization of 3-bromo-2-ethyltetrahydropyran

3-Bromo-2-ethyltetrahydropyran undergoes isomerization at 230 °C into a 6411 mixture of 7-bromo-4-heptanone and 7-bromo-3-heptanone.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1147–1149, June, 1993.     

Reaction of 3-nitro-and 3-bromo-3-nitroacrylates with sodium azide

Reactions of 3-nitro-and 3-bromo-3-nitroacrylates with sodium azide proceed as 1,3-dipolar cycloaddition and lead to the formation of triazolyl-and nitrotriazolylcarboxylates, and also of azido-and azidonitropropenoates.     

Preparation and fungitoxicity of 3-bromo-6-chloro- and 6-bromo-3-chloro-8-quinolinols

Summary 3-Bromo-6-chloro- and 6-bromo-3-chloro-8-nitro, -8-amino-, and -8-hydroxyquinolines along with 3-bromo- and 3-chloroquinolin-6,8-diols were prepared and tested for antifungal activity against six fungi (Aspergillus niger, A. oryzae, Myrothecium verrucaria, Trichoderma viride, Mucor cirinelloides, Trichophyton mentagrophytes) inSabouraud dextrose broth. Compounds with chlorine in the 3 position were generally more fungitoxic than the corresponding analogues with bromine. 6-Bromo-3-chloro-8-quinolinol inhibited four fungi at levels below 1 µg/ml andA. niger andM. cirinelloides at 2 µg/ml each.

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Synthese und Fungitoxizität von 3-Brom-6-chlor- und 6-Brom-3-chlor-8-chinolinolen

Zusammenfassung 3-Brom-6-chlor- und 6-Brom-3-chlor-8-nitro-, -8-amino- und -8-hydroxychinoline sowie 3-Brom- und 3-Chlorchinolin-6,8-diole wurden hergestellt und gegen sechs Pilzstämme (Aspergillus niger, A. oryzae, Myrothecium verrucaria, Trichoderma viride, Mucor cirinelloides, Trichophyton mentagrophytes) inSabouraud-Dextrosenährmedium auf lhre fungizide Aktivität untersucht. Verbindungen mit Chlor in Position 3 sind durchwegs fungitoxischer als die entsprechenden Bromanalogen. 6-Brom-3-chlor-8-chinolinol hemmt das Wachstum von vier Pilzen bei Konzentrationen unter 1 µg/ml und das vonA. niger undM. cirinelloides bei einer Konzentration von jeweils 2 µg/ml.

     

1-bromo-1-lithioethene: a practical reagent for the efficient preparation of 2-bromo-1-alken-3-ols

A reliable preparative-scale synthesis of 1-bromo-1-lithioethene is reported. This reagent undergoes clean 1,2-addition with a range of aldehydes and ketones at -105 degrees C to afford the corresponding 2-bromo-1-alken-3-ols in moderate to excellent yield. Efficient diastereoselective addition to alpha-siloxy and alpha-methylcyclohexanones, as well as protected 3-keto furanose sugars, is achieved in the presence of 10 mol % CeBr(3). The resulting bromoallylic alcohol adducts have considerable potential as synthetic building blocks. [reaction: see text]     

A novel synthesis of 3-bromo-1,2,4-oxadiazoles

A novel synthesis of 3-bromo-1,2,4-oxadiazoles by 1,3-dipolar cycloaddition between bromocyanogen oxide and alkyl and aryl nitriles is described.     

Benzo[b]thiophene. Derivatives. XXVIII. 5-bromo-3-benzo[b]thienylalanine and derivatives

A potential inhibitor of gelation of sickle hemoglobin, 5-bromo-3-benzo[b]thienylalanine, has been synthesized along with several derivatives. Several hydrolytic pathways from the intermediate ethyl 5-bromo-3-benzo[b]thienylformamidomalonate have been examined, and that involving alcoholysis to ethyl N-formyl-5-bromo-3-benzo[b]thienylalanine shown to be superior.     

Synthesis of substituted furan-3-carboxylates from alkyl 3-bromo-3-nitroacrylates

Carbonyl-containing furan-3-carboxylates were obtained by the refluxing of alkyl 3-bromo-3-nitroacrylates and acyclic CH-acids, namely, pentane-2,4-dione and alkyl 3-oxo-butanoates in methanol in the presence of equimolar amounts of potassium acetate. The products can be prepared by the similar processing of 2-nitro-2,3-dihydrofuran-3-carboxy-lates being the intermediates in the total transformation.     

Synthesis of 2-oxazolone-4-carboxylates from 3-nosyloxy- and 3-bromo-2-ketoesters

New methods for the synthesis of 2-oxazolone-4-carboxylates from 3-nosyloxy- and 3-bromo-2-ketoesters are described. Condensation of 3-nosyloxy-2-ketoesters with methyl carbamate in refluxing toluene in the presence of p-TSA provided 2-oxazolone-4-carboxylates in good yields (41-80%). Alternatively, bromination of alpha-ketoesters with CuBr2 provided 3-bromo-2-ketoesters which condensed with methyl carbamate in the presence of p-TSA and AgOTf under similar conditions to provide 2-oxazolone-4-carboxylates in comparable yields (30-79%). The 2-oxazolone-4-carboxylates bear functionality that can be elaborated to a variety of potentially useful compounds. For example, some of these heterocycles were readily N-acylated, reduced to alcohols, or saponified and coupled with amino acids.     

Reaction of alkyl 5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylates with zinc enolates prepared from zinc and 1-arul-2-bromo-2-phenylethanones, 2 bromoindanone, and 2-bromo-6-methyltetralone

Alkyl 5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylates react with zinc enolates prepared from 1-aryl-2-bromo-2-phenylethanones, 2-bromo indanone, 2-bromo-6-methyltetralone and zinc with formation of ethyl 4-(2-aryl-2-oxo-1-phenyl-ethyl)-5,5-dimethyl-2-oxotetrahydrofuran-3-carboxylates, alkyl 5,5-dimethyl-2-oxo-4-(1-oxoindan-2-yl)tetrahydrofuran-3-carboxylates, and ethyl 5,5-dimethyl-4-(6-methyl-1-oxo-1,2,3,4-tetrahydronaphthalen-2-yl)-2-oxotetrahydrofuran-3-carboxylates respectively, mainly as single diastereomers.     

Synthesis of methyl ester of 4-bromo-2, 3-butadienoic acid

Conclusions The synthesis of the methyl ester of 4-bromo-2, 3-butadienoic acid was described.Translated from Izvestiya Akadeemii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1494–1495, August, 1965 Original article submitted December 2, 1964     

Synthesis of 3-Alkyl-6-bromo-4,5-E-hexenoate

Two complementary routes for the preparation of 3-alkyl-6-bromo-4,5-E-hexenoate are reported.