Synthesis of 2-Methoxy-4-(methylsulfanyl)benzoic Acid — An Intermediate Product in the Preparation of the Cardiotonic Drugs Sulmazole and Isomazole

Russian Journal of Organic Chemistry - Readily available 4-methyl-3-nitrobenzenesulfonic acid and 2-methyl-5-nitrophenol were used to develop two alternative approaches to the synthesis of...     

Polymorphic Study of 2-(2-benzofuryl) Δ-2 Imidazoline

The compound 2-(2-benzofuryl) Δ-2 imidazoline, has been studied by DSC, TG, X-ray diffraction and thermomicroscopy. We shall see that in the case of a study by DSC this compound presents a strange behaviour, which apparently is in contradiction with the thermodynamic rules. In a case of monotropy, if we have the α-phase (stable) and the γ-phase (metastable), after melting and cooling only theα-phase could crystallise. But this compound can give, according to the rate of cooling, theγ-phase metastable. The rate of cooling is of fundamental importance and the monotropic behaviour of this compound will be explained using the Gibbs function G=f(T) for P=1 atm. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reactions of Methyl 1-(Bromoacetyl)azulene-3-carboxylate with 2-Hydroxy-benzaldehydes: Synthesis of 1-(Benzofuran-2-yl)-3- methoxycarbonylazulenes

A few compounds containing the 2-arylbenzofuran nucleus, have been isolated from plants.[1] For example,moracins A and B, egonol, homoegonol and (±)-machicendiol are well known.     

Convergent asymmetric synthesis of indolizidines from (S)-5-(tosylmethyl)-2-pyrrolidinone: synthesis of (−)-δ-coniceine

The enantiomerically pure (S)-5-(tosylmethyl)-2-pyrrolidinone 2, prepared from commercially available (S)-pyroglutaminol, is dialkylated at the nitrogen atom and the α-sulfonyl position using several dielectrophiles using sodium hydride as the base to diastereoselectively afford indolizidine derivatives 5 and the less common hexahydropyrrolo[1,2-a]azepin-3-one 6 in moderate to good yield. This domino process has been applied to the synthesis of (−)-δ-coniceine.     

Diastereoselective α-iminoamine rearrangement: asymmetric synthesis of (R)-(−)- and (S)-(+)-2-benzyl-2-hydroxycyclohexanone

A convenient asymmetric synthesis of both (R)-(−)- and (S)-(+)-2-benzyl-2-hydroxycyclohexanones starting from racemic 2-benzyloxycyclohexanone and the chiral auxiliary 1-phenylethylamine is reported. The route involves a [1,3]-sigmatropic shift and a new diastereoselective α-iminoamine rearrangement of a 2-benzyl-2-iminocyclohexanamine substrate.     

Furan ring opening–indole ring closure: recyclization of 2-(2-aminophenyl)furans into 2-(2-oxoalkyl)indoles

The acid-catalyzed rearrangement of 5-alkyl-2-[2-(sulfonylamino)phenyl]furans into 2-(2-oxoalkyl)indoles is described. When the N-sulfonyl group in the starting compounds was displaced by an N-acyl group, the corresponding indoles were not formed under the same reaction conditions due to the in situ indole deacylation and decomposition. The presence of an alkyl group at the C5 position of the furan ring is also crucial for the efficiency of the process. The discussed rearrangement provides a simple and efficient approach to 2-(2-oxoalkyl)indoles.     

Scope and limitations of the photooxidations of 2-(α-hydroxyalkyl)furans: synthesis of 2-hydroxy-exo-brevicomin

Photooxygenation of 2-(α-hydroxyalkyl)furans at 5 °C in MeOH followed by in situ reduction affords, in one synthetic operation, 6-hydroxy-3(2H)-pyranones and/or 5-hydroxy-2(5H)-furanones. The relative ratio of the final products is highly dependent on the substitution of the starting furan substrate. Photooxygenation of 2-(α,β-dihydroxyalkyl)furans followed by in situ reduction and ketalization with acid rapidly provides the 6,8-dioxabicyclo[3.2.1]oct-3-en-2-one framework. This new methodology was successfully applied to the synthesis of 2-hydroxy-exo-brevicomin.     

Comeplexes of 1-(2′-hydroxybenzyl)-2-(2′-hydroxyphenyl)-benzimidazole with U(VI) and Ce(IV)

Some new U(VI) and Ce(IV) complexes of 1-(2′-hydroxybenzyl)-2-(2′-hydroxyphenyl)-benzimidazole have been prepared and characterized by spectrg magnetic and conductance studies. IR spectral data suggests that the ligand in all the complexes is monodenate through the tertiary nitrogen and that the phenolic oxygen is free from coordination. Conductivity measurements indicate that the nitrate and acetate complexes of U(VI) are non-electrolytes, whereas the nitrate complex of Ce(IV) is a 1:1 electrolyte.     

Synthesis of chiral 2-(2′-pyrrolidinyl)pyridines from (S)- and (R)-proline: potential ligands of the neuronal nicotinic acetylcholine receptors

A new strategy for a straightforward synthesis of novel optically active nicotine analogues starting from (S)- and (R)-proline is reported utilizing as the key steps the inverse electron demand Diels–Alder reaction of, hitherto unknown, chiral 5-(2′-pyrrolidinyl)-1,2,4-triazines (S)- and (R)-16. These serve as appropriate precursors for the preparation of different, highly enantiomerically enriched 2-(2′-pyrrolidinyl)pyridines, modifications of natural (−)-nornicotine and (−)-nicotine and potential ligands of the neuronal nicotinic acetylcholine receptors. The multistep syntheses proceed under mild conditions, with good overall yields and with stereochemical integrity of the original stereogenic centers.     

Synthesis,spectral and RAHB studies on some arylhydrazones of β-diketones: crystal and molecular structures of 2-(2-(3-pyridyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione and 2-(2-(2-methoxyphenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione

The present study describes the synthesis and spectral analysis of a series of arylhydrazones of β-diketones (1–6) along with the single crystal X-ray structural studies of 2-(2-(3-pyridyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione (3) and 2-(2-(2-methoxyphenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione (6). Spectral and structural studies clearly exemplify the effective intramolecular hydrogen bonding and as a result the NH proton signals and carbonyl carbon signals are shifted to higher frequency region in NMR spectra. Structural implications imposed by the formation of pseudo six-membered ring after hydrogen bonding is well observed in XRD analysis. XRD analysis also evidences the envelop conformation of the dimedone ring in both the cases and resonance assisted hydrogen bonding (RAHB) studies were also performed.     

Au(III)-catalyzed tandem amination-hydration of alkynes: synthesis of α-(N-2-pyridonyl)ketones

A new Au(III)-catalyzed tandem amination-hydration reaction has been discovered, leading to the formation of α-(N-2-pyridonyl)ketones and heterocyclic analogues in good to excellent yields (14 examples, 48-90%). This reaction demonstrates the unusual use of a heterocyclic sp(2) nitrogen nucleophile in a gold-catalyzed 6-endo-dig cyclization. The tandem process allows rapid access to α-(N-2-pyridonyl)ketones, making them a convenient building block for the synthesis of more complex N-alkyl pyridone targets.     

Synthesis of 2-(2-Thienyl)benzimidazoles by the Reaction of 2-(Mercaptomethyl)benzimidazole With β-Electrophilic Esters

New 2-(2-di- and tetrahydrothienyl)benzimidazole compounds were prepared by the ring closure reactions of 2-(mercaptomethyl)benzimidazole^1,2 (1) and α,β-unsaturated compounds activated with electron-withdrawing groups.     

Bridging η2 -BO in B2(BO)3(-) and B3(BO)3(-) clusters: boronyl analogs of boranes

Anion photoelectron spectroscopy and theoretical calculations are combined to probe the structures and chemical bonding of two boron-rich oxide clusters, B(5)O(3)(-) and B(6)O(3)(-), which are shown to be appropriately formulated as B(2)(BO)(3)(-) and B(3)(BO)(3)(-), respectively. The anion clusters are found to each possess a bridging η(2)-BO group, as well as two terminal BO groups and are analogs of B(2)H(3)(-) and B(3)H(3)(-). This finding advances the boronyl chemistry and helps establish the isolobal analogy between boron-rich oxide clusters and boranes.     

Crystal Structure of 2-(4-Fluorophenylamino)-2-thiomethyl acetophenone

1mThODUCTIONThioacetalshavebeenwellstudied,becauseoftheirapplicationsinorganicsyn-thesist1i.However,aketohemithioacetalshaveseldombeeninvestigated.Inthispa-Per,wediscussedthecrystalstructureofthetitlecompoundsynthesizedbythereac-tionofabenzoylhemithioacetal(2-hydroxy-2-thiomethylacetoPhenone)and4-fluthroaniline.Sinceknowledgeofthemolecularandcrystalstructureofthetitlecom-PoundwasconsideredusefulforunderstandingthemechanismofthereactionandchemicalproPertiesofaketohemithioacetal,theX-raycr…     

A Practical Synthesis of (S)-(+)-2-(6-methoxyl-2-naphthyl) propionic Acid

a-Arylpropionic acids are an important class of non-steroidal anti-inflammatory agents1,2. The therapeutic efficacy of this class of drugs is well demonstrated by the introduction and extensive use of more than a dozen compounds exemplified by ibuprofen, naproxen, ketoprofen and flurbiprofen etc. However, in recent years the use of enantiomerical pure drugs in chemotherapy is becoming almost mandatory for enhancing specificity of drug action and reducing the toxicity. This awareness led to …     

Synthesis and Crystal Structure of 2-(4-Nitrophenyl)-1,2-benzisoselenazol-3(2H)-one DMF (1:1) Solvate

The title compound (C13H8N2O3Se-C3H7NO) has been synthesized by a simple synthetic route and by recrystallization from DMF. The molecular structure of this compound was obtained by single-crystal X-ray diffraction. The compound crystallized in the triclinic space group P with a = 7.450(6), b = 8.150(7), c = 13.859(12) , α = 75.014(14), β = 83.072(18), γ = 84.409(14)°, V = 805.0(12)3, Z = 2 and R = 0.0271 for 2575 observed reflections with I > 2σ(I). X-ray analysis reveals that not only intermolecular Se…O and C-H…O interactions, but also π…π stacking interactions exist in the adjacent molecules. The above three kinds of intermolecular interactions extend the complex into an infinite three-dimensional layered network.     

Structure and properties of BETS salts: κ-(BETS)8(Cu2Cl6)(CuCl4), θ-(BETS)2(CuCl2) and (BETS)2(CuCl4)

κ-(BETS)₈(Cu₂Cl₆)(CuCl₄) (1), θ-(BETS)₂(CuCl₂) (2), (BETS)₂(CuCl₄) (3) (BETS = bis(ethylenedithio)tetraselenafulvalene) have been prepared by diffusion-electrocrystallisation of BETS and (AsPh₄)₂(Cu₂Cl₆) solutions in chlorobenzene–ethanol. 2 has also been obtained by simple diffusion of BETS and (AsPh₄)₂(Cu₂Cl₆) solutions. 1 and 2 exhibit metal-like behaviour, down to 40 K for 1 and 4 K for 2. 3 behaves as an insulator. The crystal structures of 1, 2, and 3 are determined by X-ray diffraction methods. The structures of 1 (at 140 and 25 K) and 2 are characterised by a strong disorder of their respective anions. The crystal structure of 3 shows an unusual packing of the BETS molecules, consisting of slipped stacked (BETS)₂ dimers, leading to insulating properties. Based on the structures of 1 (at 140 and 25 K), 2 and 3, molecular and band structure calculations are carried out for the interpretation of the physical behaviours of these phases.     

Photoprotection of wool with sulfonated 2-(2′-hydroxyaryl)-2H-benzotriazoles

A range of phenolic benzotriazolesulfonic acids containing a wide variety of substituents has been synthesized. These compounds protect wool to a significant extent against photo-tendering and, in some cases, against photo-yellowing. The protective effect is dependent on the nature and position of the substituents and is enhanced by (1) locating the sulfonic acid group distant from the hydrogen-bonded phenolic group and (2) placing bulky alkyl groups ortho to this phenolic group. The protective effect of one of the best photostabilizers (II) has been studied in detail and has been found to depend on both the concentration of the photostabilizer and the pH at which it is applied. The photostabilizer (II) also protects dyed wool to some extent against photo-fading as well as against phototendering.     

Deracemization of 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH): practical synthesis of (−)-(S)-HPPH

In the presence of 10% NaOH in boiling MeOH enantiomerically enriched HPPH is racemized. This permits the deracemization of HPPH in the presence of brucine, giving enantiomerically pure (−)-(S)-HPPH [(−)-(S)-5-(4-hydroxyphenyl)-5-phenylhydandoin].