Transformation of thioacetals to cyclopropanes

Cyclopropanes were obtained by the titanocene(II)-promoted reaction of thioacetals with vinyl pivalate. It was also found that vinycyclopropanes were produced by a similar treatment of thioacetals with the titanocene(II) species in the presence of 1,3-dienes.     

Synthesis and Evaluation of Biological Activities of Bis(spiropyrazolone)cyclopropanes: A Potential Application against Leishmaniasis

This work focuses on the search and development of drugs that may become new alternatives to the commercial drugs currently available for treatment of leishmaniasis. We have designed and synthesized 12 derivatives of bis(spiropyrazolone)cyclopropanes. We then characterized their potential application in therapeutic use. For this, the in vitro biological activities against three eukaryotic models—S. cerevisiae, five cancer cell lines, and the parasite L. mexicana—were evaluated. In addition, cytotoxicity against non-cancerous mammalian cells has been evaluated and other properties of interest have been characterized, such as genotoxicity, antioxidant properties and, in silico predictive adsorption, distribution, metabolism, and excretion (ADME). The results that we present here represent a first screening, indicating two derivatives of bis(spiropyrazolone)cyclopropanes as good candidates for the treatment of leishmaniasis. They have good specificity against parasites with respect to mammalian cells.     

Structural study of di- and triorganotin(IV) dicarboxylates containing one double bond

Tri- and diorganotin(IV) dicarboxylates derived from trans-glutaconic acid and acetone 1,3-dicarboxylic acid were prepared. Their structure was studied using NMR, IR, and MS data. All of these compounds (except for compound 2a) are polymeric in the solid state and depolymerise upon dissolving in deuteriochloroform to give monomeric particles with four-coordinated central tin atoms. X-ray crystallography was used to characterize (E)-bis(tributylstannyl) pent-2-enedioate (1a). This compound crystallizes in a monoclinic space group system. The supramolecular organization of 1a can be described as layered polymeric sheets constructed of forty-membered rings that are interconnected on four different sites to the third dimension. Each layer assembled of the forty-membered rings, is made up of six triorganotin fragments and six trans-glutaconic acids, where four of them are incorporated in the core of the ring and other two are bidentate bridging and participating in the ring system by three atoms of CO₂ group only.     

Synthesis of vicinal (alkylamino)alkynylcyclopropanes from geminal alkynyl(chloro)cyclopropanes

New N-Boc-alkyl(2-alkynylcyclopropyl)amines were synthesized from 1-alkynyl-1-chlorocyclopropanes and N-Boc- alkylamines under the action of Bu^tOK in DMSO, the intermediates having been the corresponding conjugated alkynylcyclopropenes. The Boc-derivatives can be converted into free secondary 2-alkynylcyclopropylamines, as well as β-lithiated with subsequent alkylation.     

Cyclocondensation reaction of 4-aryl-4-methoxy-1,1,1-trifluoro-3-buten-2-ones with urea: Synthesis of novel 6-aryl(5-methyl)-4-trifluoromethyl-2(1H)-pyrimidinones

The synthesis of a novel series of eleven 6-aryl(5-methyl)-4-trifluoromethyl-2(1H)-pyrimidinones, where aryl=Ph, 4-CH₃Ph, 4-FPh, 4-ClPh, 4-BrPh, 4-OCH₃Ph and alkyl=H, CH₃, from the reaction of 4-aryl-4-methoxy-1,1,1-trifluoro-3-buten-2-ones with urea in the presence of hydrochloric acid, is reported. Trifluoroacetylation of acetophenone- and propiophenone-dimethylacetals derived from phenones, was employed to obtain the precursors.     

Synthesis, structural characterization and electrochemistry of C,N-chelated organotin(IV) dicarboxylates with ferrocenyl substituents

A set of C,N-chelated organotin(IV) ferrocenecarboxylates, [L^CN(n-Bu)Sn(O₂CFc)₂] (1), [(L^CN)₂Sn(O₂CFc)₂] (2), [L^CN(n-Bu)Sn(O₂CCH₂Fc)₂] (3), [L^CN(n-Bu)Sn(O₂CCH₂CH₂Fc)₂] (4), [L^CN(n-Bu)Sn(O₂CCHCHFc)₂] (5), [L^CN(n-Bu)Sn(O₂CfcPPh₂)₂] (6), [(L^CN)₂Sn(O₂CfcPPh₂)₂] (7), and [L^CN(n-Bu)₂Sn(O₂CFc)] (8) (L^CN = 2-(N,N-dimethylaminomethyl)phenyl, Fc = ferrocenyl and fc = ferrocene-1,1′-diyl) has been synthesized by metathesis of the respective organotin(IV) halides and carboxylate potassium salts and characterized by multinuclear NMR and IR spectroscopy. The spectral data indicated that the tin atoms in diorganotin(IV) dicarboxylates bearing one C,N-chelating ligand (1 and 3-6) are seven-coordinated with a distorted pentagonal bipyramidal environment around the tin constituted by the n-butyl group, the chelating L^CN ligand and bidentate carboxylate. Compounds 2 and 7 possessing two chelating L^CN ligands comprise octahedrally coordinated tin atoms and monodentate carboxylate donors, whereas compound 8 assumes a distorted trigonal bipyramidal geometry around tin with the carboxylate binding in unidentate fashion. The solid state structures determined for 1⋅C₆D₆ and 2 by single-crystal X-ray diffraction analysis are in agreement with spectroscopic data. Compounds 1, 3-5, and 8 were further studied by electrochemical methods. Whereas the oxidations of ferrocene units in bis(carboxylate) 2 and monocarboxylate 8 proceed in single steps, compound 1 undergoes two closely spaced one-electron redox waves due to two independently oxidized ferrocenyl groups. The spaced analogues of 2, compounds 3-5, again display only single waves corresponding to two-electron exchanged.     

Indium(III) chloride catalyzed one step synthesis of some new dibenzo(d,f)(1,3)dioxepines and 12H-dibenzo(d,g)(1,3)dioxocin derivatives

In the presence of catalytic amount of indium(III) chloride (10 mol %), 2,2′-dihydroxybiphenyl and bis(2-hydroxyphenyl)methane react quickly, without using any solvent, with ketones or β-keto esters possessing at least one hydrogen atom in α to the ketone-carbonyl group, to afford some new dibenzo(d,f)(1,3)dioxepines and some 12H-dibenzo(d,g)(1,3)dioxocin derivatives, respectively.     

Ferrocene Compounds. XXVII. Synthesis and Structure of 2-(Ferrocenylmethyl)propane-1,3-diol

The title compound was obtained by reduction of diethyl (ferrocenylmethyl)malonate with lithium aluminium hydride in diethyl ether. The structure of this novel ferrocene derivative was assigned by means of elemental analysis, IR, [¹H]NMR, and [¹³C]NMR spectroscopy. The structure was also confirmed by a single crystal X-ray study. The compound crystallizes in monoclinic P2₁/a space group with unit cell dimensions: a = 9.7360(6), b = 27.040(5), c = 14.767(3) Å, = 103.835(6)°, V = 3774.8(11) ų, Z = 12. The asymmetric unit contains three crystallographically independent molecules. In the ferrocenyl moieties, the Fe–C bond distance values are in the range 2.006(5)—2.051(3) Å and C–C distances in the range 1.366(7)–1.425(4) Å. The cyclopentadienyl rings in each of the molecules are mutually twisted by about 13° from the eclipsed conformation. The hydroxyl groups are involved in the intermolecular O–H...O hydrogen bond formation with O-O distances in the range 2.686(3)–2.801(4) Å forming infinite two-dimensional network in a [0 0 1] plane. The crystal structure is additionally stabilized by C–H-O weak intermolecular hydrogen bonds.     

Synthesis of sultams by cycloalkylation of (alkoxycarbonylmethane)sulfonanilides

(Methoxycarbonylmethane)sulfonanilides are alkylated by α, ω-dihaloalkanes in K₂CO₃-DMF with the formation of sultams. A high sensitivity has been detected for the reaction rate on the electronic effect of substituents in the aromatic nucleus, although substituents in the ortho position do not obstruct the reaction and in the case of 2,6-disubstituted derivatives the reaction rate and sultam yield were maximal. Tertiary sulfonamides form derivatives of 1-sulfamoylcyclopropanecarboxylic acid under these conditions. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 605–617, April, 2008.     

Pd(0) or Pd(II)-catalyzed ring-opening reactions of benzylidene- and alkylidenecyclopropyl ketones and aldehydes

Pd(0) catalyzed reactions of methylenecyclopropyl carbonyl compounds afforded a convenient method for the synthesis of conjugate (E,E)-1,3-diene derivatives 2 in good to excellent yields. Moreover, we also found that Pd(II)-catalyzed reactions of methylenecyclopropyl carbonyl compounds with water gave 1,5-diketones in good to high yields via a carbene-palladium intermediate. The plausible reaction mechanisms have also been provided on the basis of control and ¹⁸O-labeling experiments.     

Synthesis of (R,S)-muscone

Construction of the carbon-skeleton of (R,S)-muscone was achieved by reacting methyllithium with the dianion of cyclopentadecanedione-1,3, itself accessible by hydration of cyclopentadecanediyne-1,3.

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Synthese von (R,S)-Muscon (Kurze Mitteilung) Short communication

Zusammenfassung Die Konstruktion des Kohlenstoffgerüstes von (R,S)-Muscon gelingt durch Reaktion des Dianions von Cyclopentadecandion-1,3, das durch Hydratisierung von Cyclopentadecandiin mit Methyllithium erhältlich ist.

     

Reinvestigation of the synthetic and mechanistic aspects of Mn(III) acetate mediated oxidation of enones

Mn(OAc)₃ mediated α′-acetoxylation of α,β-unsaturated enones is reinvestigated from a synthetic and mechanistic point of view and an improved procedure based on the use of acetic acid as a co-solvent is presented. Excellent results were obtained for a variety of structurally diverse and synthetically important enones under the optimized conditions.     

Synthesis of 3-deoxy-3,3-difluoro-d-ribohexose from gem-difluorohomoallyl alcohol

A novel synthetic route to 3-deoxy-3,3-difluoro-d-ribohexose 1 has been developed. Dihydroxidation of gem-difluorohomoallyl alcohol followed by several steps of protection and deprotection gave key intermediate 9. Oxidation of 1,5-diol 9 with 2 equiv. trichloroisocyanuric acid and catalytic TEMPO gave lactone 10. Reduction of 10 with DIBAL-H followed by deprotections afforded the target molecule 1.     

Synthesis of new 1,3-bis（phenylethynyl）disilazanes

Three new 1,3-bis(phenylethynyl)disilazanes were synthesized from the reaction of 1,3-dichlorodisilazanes with (phenylethy- nyl)lithium,and characterized by infrared (IR) spectra,nuclear magnetic resonance (NMR) and mass spectrometry (MS).     

Rearrangement of N-alkyl 1,2-amino alcohols. Synthesis of (S)-toliprolol and (S)-propanolol

N-alkyl 1,2-amino alcohols were rearranged stereospecifically by using TFAA/Et₃N. This rearrangement has been used to synthesize N-isopropyl-3-(aryloxy)-2-hydroxypropylamines, β-adrenergic blocking agents such as (S)-toliprolol and (S)-propanolol.     

Synthesis and applications of surface-grafted Th(IV)-imprinted polymers for selective solid-phase extraction of thorium(IV)

A new functional monomer N-(o-carboxyphenyl)maleamic acid (CPMA) was synthesized and chosen for the preparation of surface-grafted ion-imprinted polymers (IIPs) specific for thorium(IV). Polymerizable double bond was introduced to silica gel surface by amidation reaction between -NH₂ and maleic anhydride. In the ion-imprinting process, thorium(IV) was complexed with the carboxyl groups, then was imprinted in the polymers grafted to the silica gel surface. The imprinted Th(IV) was removed with 3 mol L⁻¹ HCl. The obtained imprinted particles exhibited excellent selectivity and rapid kinetics process for Th(IV). The relatively selective factor (α_r) values of Th(IV)/La(III), Th(IV)/Ce(III), Th(IV)/Nd(III), Th(IV)/U(VI), and Th(IV)/Zr(IV) were 85.7, 88.9, 26.6, 64.4, and 433.8, respectively, which were greater than 1. The precision (R.S.D.), the detection limit (3σ), and the quantification limit (10σ) of the method were 1.9%, 0.51 ng mL⁻¹ and 1.19 ng mL⁻¹, respectively. The prepared IIPs as solid-phase extractants were successfully applied for the preconcentration of trace thorium in natural and certified samples prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES) with satisfactory results.     

Vinyl-aziridines and cyclopropanes in Pd-catalyzed (3+2)-cycloaddition reactions with cyclic N-sulfonyl imines

Efficient palladium-catalyzed (3 + 2)-cycloaddition reactions of cyclic N-sulfonyl imines and vinyl-aziridines (or cyclopropanes) have been achieved. The reactions, with either vinylic substrate, proceed with excellent yields affording highly functionalized imidazolidine and pyrrolidine derivatives. The cycloadditions take place via the reaction of zwitterionic π-allyl palladium intermediates with cyclic N-sulfonyl imines through i) the formation of two NC bonds in the presence of vinylaziridines (synthesis of imidazolidines) and ii) one CC bond and one NC bond in the presence of vinylcyclopropanes (synthesis of pyrrolidines). Following on preliminary works on the diastereoselective synthesis of imidazolidines, herein we wish to give a broader view on the subject by describing derivatization reactions and attempts towards an enantioselective version. Moreover, we describe and discuss the behavior of each vinylic substrate (aziridine or cyclopropane) on the (3 + 2)-cycloaddition reactions. Mechanistic and (intriguing) selectivity outcomes are also going to be discussed.     

Gold(I)-catalyzed double migration cascades toward (1E,3E)-dienes and naphthalenes

A novel gold(I)-catalyzed cascade cycloisomerization of a variety of propargylic esters leading to unsymmetrically substituted naphthalenes has been developed. This domino process involves an unprecedented tandem sequence of 1,3- and 1,2-migrations of two substantially different migrating groups. It is believed that this transformation proceeds via formation of 1,3-diene intermediate or its equivalent, which, upon carbocyclization and aromatization steps, transforms into the naphthalene skeleton. In addition, it was also demonstrated that a variety of 1,3-dienes can be accessed stereoselectively via the 1,3-migration-proton transfer cascade.     

Synthesis of novel ferrocene containing vic-dioxime ligands and their Ni(II), Cu(II) and Co(II) complexes: Spectral, electrochemical and biological activity studies

Two new vic-dioxime ligands bearing an important redox-active substituent, anti-β-ferrocenylethylaminoglyoxime (1a) and anti-β-ferrocenylethylaminophenylglyoxime (1b), have been synthesized, and their Ni(II), Cu(II) and Co(II) (2a-4a, 2b-4b) complexes were obtained. The composition and structure of the products were determined by elemental analysis, Fourier transform infrared (FT-IR), ultraviolet-visible (UV-vis), mass spectrometry (MS), one-dimensional (1D) ¹H, ¹³C NMR, and two-dimensional (2D) heteronuclear multiple bond correlation (HMBC) techniques. The redox behaviors of the ligands and their complexes were investigated by cyclic voltammetry (CV), which revealed that all the ferrocenyl redox centers are electrochemically independent and undergo a quasi-reversible oxidation at similar potentials. Also, antibacterial activity was studied against Staphylococcus aureus ATCC 29213, Streptococcus mutans RSHM 676, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. The antimicrobial test results indicated that all the compounds have mild levels of antibacterial activity against both gram negative and gram-positive bacterial species.