Simple method for the preparation of cyclopentadienyliron tricarbonyl salts

Conclusions A simple method was developed for the preparation of cyclopentadienyl tricarbonyl salts by the reaction of [C₅H₅Fe(CO)₂]₂ with CO and ferric sulfate upon heating in methanol.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2147–2148, September, 1984.     

A facile preparation of backbone-substituted, functionalized and chiral imidazolinium salts

A versatile and modular method for the preparation of various backbone-substituted, functionalized and chiral imidazolinium salts from the reaction of formamidines with alkene oxides has been described, providing a more straightforward access to substituted imidazolinium salts than the previously reported methods.     

Synthesis and crystal structure of 4-acetoxy-5,6-dihydro-5,5-dinitro-2H-1,3-oxazineN-oxide

A novel heterocyclic compound, 4-acetoxy-5,6-dihydro-5,5-dinitro-2H-1,3-oxazineN-oxide, has been synthesized by the reaction of the dipotassium salt of 1,1,5,5-tetranitro-3-oxapentane with aqueous acetic acid. The synthesized compound has been studied by X-ray diffraction analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2207–2210, December, 1994.We would like to thank G. V. Lagodzinskaya (Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences) for recording and interpreting¹H NMR spectra, A. M. Korolev (Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences) for helpful discussion, and V. I. Fetisov (Institute of Physiologically Active Compounds, Russian Academy of Sciences) for performing quantum-chemical calculations by the AM1 SCF MO LCAO method.     

Practical synthetic approach to 4-acetoxy-2-azetidinone for the preparation of carbapenem and penem antibiotics

A practical synthesis of 4-acetoxy-2-azetidinone useful for the preparation of carbapenem- and penem-type antibiotics is described. The synthesis has advantages such as avoiding the tedious and costly column chromatographic or recrystallized separation steps for diastereomers. The overall yield of the product is greatly improved and the process is also more economical for large-scale production. In addition, the mechanism for oxidative decarboxylation is also present.     

New biionic transition metal complexes based on the salen ligands: synthesis and application as synthons in the preparation of chiral homo- and heterobimetallic systems

A new approach was used for the development of chiral homo- and heterobimetallic systems resulting in the preparation of four original bimetallic systems, two of which were studied by X-ray diffraction.     

A new method for the preparation of 2,3-cycloalkeno-5,6-cycloalkeno-4H-pyran-4-ones

Several 2,3-cycloalkeno-5,6-cycloalkeno-4H-pyran-4-ones, such as 2,3,5,6-bicyclopenteno-4H-pyran-4-one and 1,2-dihydronaphtho[3,4-b]cyclopenteno[1,2-e]-4H-pyran-4-one, were synthesized conveniently by the reaction of a cyclic ketone enamine and diacylchloride. This reaction allows a new method for preparation of these compounds, which may be the precursors for the synthesis of some useful heterocycles.     

Multicomponent reaction for the synthesis of highly functionalized piperidine scaffolds catalyzed by TMSI

Research on Chemical Intermediates - An efficient method for the synthesis of highly functionalized piperidines via one-pot domino reaction of β-ketoesters, aromatic aldehydes, and aromatic...     

Stereoselective synthesis of 2-aryl-4-en-1-ols,promising synthons for the preparation of oxygen heterocycles

Reactions of arylacetic acids with N-methoxymethanamine afford corresponding Weinreb amides which at alkenylation with methallyl and prenyl bromides in the presence of (Me₃Si)₂N^–Na⁺ form unsaturated amides ArCHRCONMe(OMe) (R = CH₂CMe=CH₂, CH₂C=CMe₂). Amides readily react with BuLi and BnMgCl to give ketones ArCHRCOR' (R' = Bu, Bn). A stereoselective reduction of the latter with LiBH(s-Bu)₃ leads to a quantitative formation of syn-isomers of 2-aryl-4-en-1-ols.     

4-Fluoropyrrolidine-2-carbonyl fluorides: useful synthons and their facile preparation with 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride

4-Fluoropyrrolidine derivatives are useful in medicinal chemistry applications such as dipeptidyl peptidase IV inhibitors. As attractive synthons for these, N-protected (2S,4S)-4-fluoropyrrolidine-2-carbonyl fluorides were synthesized in high yield by double fluorination of N-protected (2S,4R)-4-hydroxyproline with 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (Fluolead). The 4-fluoropyrrolidine-2-carbonyl fluorides were converted to useful intermediates such as 4-fluoropyrrolidine-2-carboxamides, -N-methoxy-N-methylcarboxamide (Weinreb amide), -carboxylate methyl esters, and -carbonitriles in excellent yields. The crystalline N-Fmoc-cis-4-fluoropyrrolidine-2-carbonyl fluoride 2a is a particularly useful synthon due to its high yield of preparation and easy isolation as an enantiomerically pure compound by crystallization. Thus, the methodology using the synthons prepared by the stereospecific double fluorination has enabled a significant decrease in the synthetic steps needed for the preparation of the 4-fluoropyrrolidine derivatives useful for medicinal applications.     

Fluorinated cyclohexadienones as versatile synthons for preparation of organofluorine compounds

The review summarizes the new investigation of the reactivity of polyfluorinated cyclohexadienones: nucleophilic, cycloaddition, and photochemical reactions and, furthermore, such transformations of products of these reactions as reduction, hydrolysis, and photochemical reaction. The use of polyfluorinated cyclohexadienones as highly reactive synthons opens the possibility for the synthesis of a broad variety of otherwise inaccessible fluorinated organic compounds containing functional groups, such as fluorinated derivatives of polyphenyl ethers, arylacetic acids, cyclohexenecarboxylic acids, naphthalene and anthraquinone derivatives bearing the carboxylic group, and some fluorinated heterocyclic compounds.     

4-Methylenedioxolan-2-ones as convenient synthons for the preparation of natural products of the berbine and calycotomine series

Intramolecular amidoalkylation of nonactivated 3-(2-arylethyl)-4-hydroxyoxazolidin-2-ones in polyphosphoric acid gave oxazolo[4,3-a]isoquinolin-3-one whose hydrolysis affords isoquinoline β-amino alcohols, calycotomine analogs. Using the developed procedure, 13,13,13a-trimethylberbine was synthesized. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 548–554, March, 2006.     

Silylated iminophosphonates: Novel reactive synthons for the preparation of fluorinated aminophosphonates and aminophosphonic acids

A convenient synthetic approach towards previously unknown N- and N,O-silylated α-iminophosphonates bearing fluoroalkyl groups at the imine C atom was developed. The synthetic potential of the compounds was demonstrated by their easy functionalization and the straightforward preparation of biorelevant aminophosphonates and free aminophosphonic acids with heterocyclic residues in the α-position.     

Evaluation of Zard trifluoromethylketone synthesis for the preparation of potential bifunctional fluorinated synthons

In the quest for potential bifunctional fluorinated synthons, we examined the behavior of chlorodifluoroacetic and hexafluoroglutaric anhydride in their reaction with acid chlorides in the presence of pyridine under the conditions of Zard trifluoromethylketone synthesis. Chlorodifluoroacetic anhydride led easily to the expected chlorodifluoromethyl ketones in the case of relatively non-encumbered primary acid chlorides. In the case of hexafluoroglutaric anhydride we observed the unexpected formation of α substituted hexafluorocyclohexane-1,3-dione derivatives among with the corresponding fluorinated 3-chloro-cyclohexenones.     

Convenient preparation of (4-iodophenyl)aryliodonium salts

The (4-iodophenyl)aryliodonium salts bis(4-iodophenyl)iodonium, (4-iodophenyl)(4-methoxy-phenyl)iodonium and (4-iodophenyl)(2-thienyl)iodonium, each with three different anions, were prepared using 4-iodo-1-[hydroxy(tosyloxy)iodo]benzene. These are suitable precursor molecules for electrophilic radiofluorination and other 4-iodophenylation reactions, whose products can subsequently serve as reagents for transition metal catalysed cross coupling and other metal organic reactions.     

Efficient preparation of 4-methoxy-5,6-dihydro-2H-pyran

We report the efficient synthesis of 4-methoxy-5,6-dihydro-2H-pyran (MDHP) via the TiCl₄ driven elimination of MeOH from 4,4-dimethoxytetrahydropyran. The previous difficulty of preparing MDHP restricted the wider use of 4-methoxytetrahydropyran-4-yl (MTHP) acyclic acetals, which have desirable protecting group properties when compared to more commonly used MOM- and THP-acetals. The behaviour of the elimination on related acetals is also examined.     

Novel preparation of functionalized iodotetrahydronaphthyridine, iodoazaindoline, and iodotetrahydropyridoazepine systems

A novel method, which utilizes a key halogen dance step for the preparation of iodotetrahydronaphthyridine, iodoazaindoline, and iodotetrahydropyridoazepine ring-systems is described. A variety of transformations of the iodo-functional group are also reported to demonstrate the utility of this method.     

Asymmetric synthesis of functionalized piperidine derivatives: synthesis of (S)-anatabine

A short and efficient chiral synthesis of 6-aryl-5-phenylsulfonyl-1,2,5,6-tetrahydropyridines was achieved in moderate yield and with good selectivity. The absolute configurations were assigned by extending the methodology to (S)-anatabine and as well with NMR experiments.