Facile stereoselective synthesis of cis- and trans-3-alkoxyazetidin-2-ones

A highly stereoselective synthesis of cis- and trans-3-alkoxy-3-phenyl/benzylthioazetidin-2-ones is described. The reaction of α-chlorosulfide-β-lactams with various alcohols catalyzed by a Lewis acid such as ZnCl₂ in the presence of molecular sieves (3-4 Å) leads to cis-3-alkoxy-3-phenyl/benzylthio-β-lactams whereas treatment of potassium 2-alkoxy-2-phenylthioethanoate with appropriate Schiff's base using POCl₃ in the presence of triethylamine leads to the formation of trans-3-alkoxy-3-phenylthioazetidin-2-ones as major products.     

Synthesis of 3-alkoxy-2-nitroxypropyl-N-alkylnitramines

It was shown that 3-alkoxy-2-nitroxypropyl-N-alkylnitramines can be prepared by nitration of the corresponding 3-alkoxy-2-hydroxypropyl-N-alkylsulfamates. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1987–1989, November, 1997.     

N-arylation of 3-alkoxypyrazoles, the case of the pyridines

In the course of a research program focused on the preparation of libraries of new chemical entities derived from 3-alkoxypyrazoles, we studied their N-pyridylation using 2, 3 or 4-bromopyridines. This was achieved using Cristau and Taillefer copper-catalyzed arylation method and mostly led to the 3-alkoxy-1H-pyrazol-1-yl pyridine isomer along with lesser amount of the alternative 5-alkoxy-1H-pyrazol-1-yl pyridine. The structures of these isomers were often established via their chemical transformations and sometimes recourse to unambiguous synthetic routes for comparison purposes. The alternative use of 2-fluoropyridine-based arylation was also investigated and lifted some of the limitations encountered in the course of this study.     

Synthesis of 5-alkoxy-3-amino-7-nitro-1,2,4-benzotriazine 1-oxides from 1,3,5-trinitrobenzene

1-Alkoxy-3,5-dinitrobenzenes were nitrated to give 1-alkoxy-2,3,5-trinitrobenzenes. The reaction of the latter with guanidine affordsN-(2-alkoxy-4,6-dinitrophenyl)guanidines, which undergo cyclization under the action of KOH to form 5-alkoxy-3-amino-7-nitro-1,2,4-benzotriazine 1-oxides. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1650–1652, September, 2000.     

Synthesis of functionalized 2-alkoxybenzoates, 2-aryloxybenzoates and xanthones based on formal [3+3] cyclocondensations of 3-alkoxy- and 3-aryloxy-1-silyloxy-1,3-butadienes with 3-silyloxy-2-en-1-ones

Functionalized 2-alkoxy- and 2-aryloxybenzoates were prepared by formal [3+3] cyclocondensations of 3-alkoxy- and 3-aryloxy-1-silyloxy-1,3-butadienes with 3-silyloxy-2-en-1-ones. The reaction of 2-aryloxybenzoates with concentrated sulfuric acid resulted in the formation of xanthones.     

Expeditious synthesis of 2,3-dihydro-2-alkoxy-3-methylenebenzofurans from N-benzofuran-3-ylmethyl N,N,N-trialkylammonium bromides: a new approach to access the natural product, 2-hydroxy-3-methylene-6-methyl-2, 3-dihydrobenzofuran

A highly efficient strategy was developed to construct a natural product-based library of 2-alkoxy-3-methylene-2,3-dihydrobenzofurans from N-benzofuran-3-ylmethyl N,N,N-trialkylammonium bromides.     

Synthesis of 1-alkoxy-3-(2-hydroxyethyl)-1-triazene 2-oxides

Synthetic procedure to access the first representatives of a new series of 3-monosubstitued functional derivatives of 1-alkoxy-1-triazene 2-oxides, i.e., 1-alkoxy-3-(2-hydroxyethyl)- and 1-alkoxy-3-(2-acetoxyethyl)-1-triazene 2-oxides, were elaborated. 1-Alkoxy-3,3-bis(2-hydroxyethyl)-1-triazene 2-oxides were used to derive 3-(2-acetoxyethyl)-, 3-(2-bromoethyl)- and 3-(2-cyanoethyl)substituted 1-alkoxy-3-(2-acetoxyethyl)-1-triazene 2-oxides.     

Selective catalytic sp3 C-O bond cleavage with C-N bond formation in 3-alkoxy-1-propanols

The ruthenium catalyzed selective sp(3) C-O cleavage with amide formation was reported in reactions of 3-alkoxy-1-propanol derivatives and amines. The cleavage only occurs at the C3-O position even with 3-benzyloxy-1-propanol. Based on the experimental results, O-bound and C-bound Ru enolate complexes were proposed as key intermediates for the unique selective sp(3) C-O bond cleavage in 3-alkoxy-1-propanols.     

Nitrogen's reactivity of various 3-alkoxypyrazoles

Our current interest in the design of original chemical libraries featuring a pyrazole nucleus led us to focus on the chemistry of the 3-alkoxy-5-methylpyrazoles we have recently made readily available. With in mind the preparation of an array of the less accessible 1-arylpyrazol-3-ones, the present report describes the respective nitrogen's reactivity of various 3-alkoxypyrazoles toward arylation reaction, using arylboronic acids, as well as alkylation reactions using methyl iodide or benzylbromide. The structure assignments of the isomers obtained were achieved using long distance ¹⁵N-¹H NMR correlation measurements or by the recourse to unambiguous synthetic pathways.     

Reactions of (Z)-3-aryl-3-chloropropenals with nucleophiles: stereoselective formation of (E)-vinylogous esters, (E)-vinylogous amides, and vinamidinium salts

The highly stereoselective conversions of (Z)-3-aryl-3-chloropropenals to (E)-3-alkoxy-3-arylpropenals, to (E)-3-aryl-3-morphorlinopropenals, and to vinamidinium salts are reported. The stereochemical assignments were based on 2D-NMR experiments.     

Preparative synthesis of 1,2-propyleneglycolacetals of 3-alkoxy-4-acyloxybenzaldehydes

The article describes a preparative method for the synthesis of new 1,2-propyleneglycolacetals of 3-alkoxy-4-acyloxy-benzaldehydes obtained by condensation of 3-alkoxy-4-acyloxybenzaldehydes with 1,2-propylene glycol in the medium of boiling benzene in the presence of the FIBAN K-1 sulfonic cation-exchange resin.     

Synthesis of optically active 3-alkoxy-6-hydroxymethyl-6-methyl-2-cyclohexenone

Optically active 3-alkoxy-6-hydroxymethyl-6-methyl-2-cyclohexenone and 6-acetoxymethyl-3-alkoxy-6-methyl-2-cyclohexenone were efficiently obtained by lipase-catalyzed kinetic resolution. (R)-6-Acetoxymethyl-3-(methoxymethoxy)-6-methyl-2-cyclohexenone was converted to the synthetic intermediate of cassiol.     

Convenient synthesis of 3-alkoxy-3-aryloxindoles by intramolecular arylation of mandelic amides

Medicinally important 3-alkoxy-3-aryloxindoles are conveniently prepared by the rapid microwave-promoted palladium-catalyzed intramolecular enolate arylation of mandelate-derived anilides.     

N-(2-Pyridyl)amides of 2,4-Dioxobutyric Acids in Reactions with Diazoalkanes

N-(2-Pyridyl)amides of 4-R-2-alkoxy-4-arylcrotonic acids and 3-alkoxy-3-aroylmethyl-2-oxo-2,3-dihydroimidazo[1,2-a]pyridines have been synthesized by the interaction of N-(2-pyridyl)amides of 4-aryl-2,4-dioxobutyric acids with diazoalkanes. The structure and mechanism of formation of the products are discussed.     

2-Alkoxy-3-substituted-4-quinolinols from the thermal reactions of N-phenylketenimines bearing ester groups

Several ketenimines bearing ester groups were prepared and their thermal reactions gave 2-alkoxy-3-substituted-4-quinolinols VIa-e via presumed iminoketene intermediates. Subsequent oxidation of 2-alkoxy-3-(3-methylbut-2-enyl)-4-quinolinols VIc and VId provided pyranoquinolines VIIIa and VIIIb.     

Studies on pyrazines. 24 . A simple and versatile synthetic method for 3-alkoxy- and 3-aminopyrazinecarbonitriles

New and concise synthetic methods of 3-alkoxy- and 3-aminopyrazinecarbonitriles by nucleophilic displacement of 3-phenylsulfonylpyrazinecarbonitriles are reported.     

Photochemical and thermal addition of alcohols to 2-cyanofuran : 1-alkoxy-2-cyanocyclopropane-3-carboxaldehydes; 2-alkoxy-3-cyano-2, 3-dihydrofuran; 1-alkoxy-1-(2-furan)-methylenimine; photochemical ring contraction; cis-trans-isomerization of dihydrofurans

The photolysis of 2-cyanofuran in alcohols yields 1-alkoxy-2-cyanocyclopropane-3-carboxaldehydes as the major products, which rearrange thermally to trans-2-alkoxy-3-cyano-2,3-dihydrofurans and small amounts of cis-isomers. Thermal mutual rearrangements between trans- and cis-2- alkoxy-3-cyano-2, 3-dihydrofurans were studied. Liquid phase thermal addition of alcohols in a temperature range between 100° and 200° yields 1-alkoxy-1-(2-furan)-methylenimines, which rearrange photochemically to 2-furyl-methylamino-ketone in case of the methoxy derivative. 3-Cyano-furan does not yield photoaddition or thermal addition products. The different behaviors of 2- and 3-substituted furans are discussed.     

Stereoselective synthesis of Z-3-alkoxy-2-[(4′-methoxyphenyl)methylidene]-1(3H)-isobenzofuranones

Photoreorganisation of 2-alkoxy-2-(4′-methoxyphenyl)-1H-indene-1,3(2H)-diones in anhydrous acetone affords exclusively Z-3-alkoxy-3-[(4′-methoxyphenyl)methylidene]-1(3H)-isobenzofuranones. The products were identified by X-ray crystallography of one of them.     

An efficient synthesis of ferrocenyl substituted 3-cyanopyridine derivatives under ultrasound irradiation

An efficient synthesis of 2-alkoxy-4-aryl-6-ferrocenyl-3-cyanopyridines via the condensation of ferrocenyl substituted chalcones with malononitrile in a freshly prepared sodium alkoxide solution under ultrasound irradiation was investigated. Especially noteworthy, the reaction of 1-ferrocenyl-3-(pyridin-2-yl)prop-2-ene-1-one with malononitrile afforded 2-alkoxy-4-pyridyl-6-ferrocenylpyridine, with the loss of CN group on the 3-position of pyridine ring was first observed.     

1-Trimethoxysilylmethyl-and 1-(2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecan-1-ylmethyl)-1,1-dimethyl-2-(3-alkoxy-3-oxopropyl)hydrazinium halides

Previously unknown 1,1-dimethyl-1-trimethoxysilylmethyl-2-(3-alkoxy-3-oxopropyl)hydrazinium and 1,1-dimethyl-1-(2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecan-1-ylmethyl)-2-(3-alkoxy-3-oxopropyl)-hydrazinium halides were synthesized, and physiological activity of 2-(3-ethoxy-3-oxopropyl)-1,1-dimethyl-1-(2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecan-1-ylmethyl)hydrazinium chloride and bromide was studied.