Facile synthesis of two oxocan derivatives using some chemical strategies

There are several studies for the synthesis of oxacycle derivatives using some reagents which require special conditions have been reported. The aim of this study was to synthesize two oxocan derivatives from either imidazole or 2-methylimidazole. The chemical structure was evaluated through both ¹H NMR and ¹³C NMR spectroscopic analysis. The results showed a moderate yielding from oxocan derivatives. It should be mentioned that reagents used in this investigation are not expensive and do not require special conditions for handling.     

Recent advance in heterocyclic organozinc and organomanganese compounds; direct synthetic routes and application in organic synthesis

A practical synthetic route for the preparation of 2-pyridyl and 3-pyridyl derivatives has been accomplished by utilizing a simple coupling reaction of stable 2-pyridylzinc bromides and 3-pyridylzinc bromides. The organozincs used in this study were easily prepared via the direct insertion of active zinc into the corresponding bromopyridines. The subsequent coupling reactions with a variety of different electrophiles have afforded the corresponding coupling products. Using highly active manganese, a variety of Grignard-type organomanganese reagents have been obtained. The subsequent coupling reactions of the resulting organomanganese reagents with several electrophiles have also been accomplished under mild conditions.     

Design and synthesis of two triazonine-carbaldehyde derivatives using several chemical tools

Several triazonine-carbaldehyde derivatives have been prepared using different protocols; however, some require special reagents and conditions. The aim of study involved the synthesis of two triazonine-carbaldehyde derivative using testosterone or OTBS-testosterone as chemical tool. Triazonine-carbaldehyde derivatives were prepared by a series of reactions that involve the following: (1) synthesis of two nitrobenzamide derivatives by reaction of testosterone or OTBS-testosterone with p-nitrobenzoyl azide using Copper(II) as catalyst; (2) reaction of the nitrobenzamides with ethylenediamine to form two triazonine derivatives using boric acid as catalyst; (3) preparation of hexynyl-triazonine derivatives by the reaction of two triazonines 6-chlorohex-1-yne in basic medium; (4) reaction of hexynyl-triazonine derivatives with benzaldehyde to form two triazoninol analogs; (5) preparation of triazoninynal derivatives through oxidation of triazoninol analogs with dimethyl sulfoxide; and (6) synthesis of triazonine-carbaldehyde derivatives by the reaction of triazoninynal derivatives with hexyne-1 using Copper(II) as catalyst. The chemical structure of compounds was determined by spectroscopic and spectrometric methods. In conclusion, in this work were prepared two triazoninone derivatives using several chemical techniques, which are simple procedures and easy to handle.     

The Synthesis and Reactions of Yomogi Alcohol. Conversion of the artemisyl skeleton to the santolinyl skeleton by a 1,2-shift of a vinyl group. Synthesis of santolinatriene

The synthesis of yomogi alcohol (2, 5, 5-trimethylhepta-3,6-dien-2-ol, 2 ) is described, and experiments directed towards its allylic rearrangement to artemisia alcohol detervatives have been carried out. Acidic reagents open the ring of yomogi alcohol epoxide ( 16 ) at with participation of the 6,7-double-bond, a shift of the vinyl group results to yield a compound with the santolinyl skeleton. The same reagents are without effect when this double bond reduced. Action of butyllithium of the benzaldehyde acetal ( 41 ) of 2, 5-dimethyl-4-vinyl-2, dihydroxy-hex-5-ene ( 28 ), obtained by acid-catalyzed ring opening of yomogi alcohol epoxide in the presence of benzaldehyde, leads to santolinatriene ( 42 ). This vinyl shift is not observed in the case of O-acetyl yomogi alcohol epoxide ( 46 ), from white a compound believed to be an oxetan 48 (R ? COCH₃) is formed with concomitent shift of the acetate group. Further unusual reactions of the oxetan are described, and some observation about the epoxidation of sterically hindered allyl alcohols and their acetates are made.     

Diastereoselective Weitz-Scheffer epoxidation of levoglucosenone for the synthesis of isolevoglucosenone and derivatives

High-yielding epoxidation conditions for the cellulose pyrolysis product (?)-levoglucosenone (LGO) and 3-aryl derivatives of LGO have been developed. The reaction of LGO with hydrogen peroxide/base is known to give a Baeyer-Villiger reaction, however, it was found that the reactions of LGO or derivatives with tert-butylhydroperoxide/base affords solely epoxides through the Weitz-Scheffer reaction. A critical parameter in the successful isolation of the epoxide from LGO was to avoid all contact with water or alcohols during the reaction and workup. The epoxide products were reacted under Wharton conditions affording allylic alcohols and subsequent oxidation led to isolevoglucosenone or 3-arylisolevoglucosenone derivatives. Previously unreported reactions on isolevoglucosenone were then investigated.     

Effect of metal ions in organic synthesis. Part XIV. A mild,simple, and convenient method for the synthesis of 1-(arylamino)pyrrole derivatives by copper(II) ion-catalyzed reaction of (arylazo)alkenes and 1,3-dicarbonyl compounds

A mild, simple and convenient method for the synthesis of some 1-(arylamino)pyrrole derivatives by copper(II) ion-catalyzed reaction of (arylazo)alkenes and 1, 3-dicarbonyl compounds is reported. These reactions take place under magnetic stirring at room temperature, do not require a strong acid or base, nor expensive or difficultly available reagents, nor even complicated procedures. The synthesis seems to be successfully applicable to different (arylazo)alkenes, 1, 3-diketones and ß-ketoesters, and frequently occurs with good yields.     

Phenol-containing macrocyclic diamides as new catalysts in the highly regioselective conversion of epoxides to beta-hydroxy thiocyanates.

The regioselective ring-opening reactions of some epoxides with ammonium thiocyanate in the presence of a series of new phenol-containing macrocyclic diamides and also dibenzo-18-crown-6-, 18-crown-6-, benzo-15-crown-5-, and pyridine-containing macrocyclic diamide have been studied. The epoxides were subject to cleavage by NH(4)SCN in the presence of these catalysts under mild reaction conditions in various aprotic solvents. In this study, reagents and conditions have been discovered with which the individual beta-hydroxy thiocyanates can be synthesized in high yield and with more than 90% regioselectivity. The results can be discussed in terms of a four-step mechanism: (1) formation of complex between catalyst and NH(4)SCN, (2) release of SCN(-) nucleophile from the complex, (3) reaction of the active nucleophile at the less sterically hindered site in the epoxide, and (4) regeneration of catalyst. The major advantages of this method are as follows: (1) high regioselectivity, (2) simple regeneration of catalyst, (3) its reuse through several cycles without a decrease in activity, and (4) ease of workup of the reaction.     

Studies on antiatherosclerotic agents. Synthesis of 7-ethoxycarbonyl-4-formyl-6,8-dimethyl-1(2H)-phthalazinone derivatives and related compounds

Derivatives of 7-ethoxycarbonyl-4-formyl-6,8-dimethyl-1(2H)-phthalazinone and closely related compounds were synthesized using Wittig and epoxidation reactions. Ring opening amination of the epoxides were carried out using dimethylaluminum amide reagents under mild reaction conditions. beta-Keto ester and beta-diketone moieties were introduced through diazo derivatives. These moieties were reacted with hydrazine hydrate to produce 4-pyrazolyl derivatives. The derivatives were tested for their inhibitory effect on platelet aggregation, and their relaxing effect on blood vessels.     

An efficient synthesis of mimetics of neamine for RNA recognition

As mimetics of neamine, several 4-heterocyclic 2-deoxystreptamine derivatives were chemically synthesized for RNA recognition. Conversion of 4-methylthiomethyl-5,6-di-O-acetyl-diazido-2-deoxystreptamine to the 4-chloromethyl derivative followed by reactions with different nuclophilic reagents gave the 4-heterocyclic 2-deoxystreptamine derivatives in satisfactory yields.     

Reactions of substituted (1,3-butadiene-1,4-diyl)magnesium, 1,4-bis(bromomagnesio)butadienes and 1,4-dilithiobutadienes with ketones, aldehydes and PhNO to yield cyclopentadiene derivatives and N-Ph pyrroles by cyclodialkenylation

1,4-Dilithiobutadiene derivatives 1, 1,4-bis(bromomagnesio)butadiene derivatives 2 and metallacyclic (1,3-butadiene-1,4-diyl)magnesium reagents 3 were prepared and their reactions with ketones, aldehydes, and PhNO were investigated. Multiply substituted cyclopentadienes and N-Ph pyrroles were formed by unprecedented reaction conditions. The carbonyl group of aldehydes and ketones was deoxygenated during the reaction and behaved formally as a one-carbon unit; the N==O moiety of PhNO was cleaved to afford N-Ph pyrrole derivatives. Furthermore, different reactivities among these three types of reagents 1, 2 and 3 were revealed. The 1,4-dilithium reagents 1 readily reacted with both aldehydes and ketones; the 1,4-dimagnesium reagents 2 reacted with aldehydes, but not ketones; the metallacyclopentadiene reagents of magnesium 3 showed higher reactivity and did react with ketones.     

Design and synthesis of a bismethylsulfanyl-steroid-azetyl butanol derivative from 2-nitroestradiol

Several studies for the synthesis of polycyclic derivatives have been reported; however, there is little information on the preparation of steroid-polycyclic derivatives. In this way, the aim of this study was to synthesize a bismethylsulfanyl-steroid-azetyl butanol derivative (compound 10 ) from 2-nitroestrone. The chemical structure was evaluated through both ¹H NMR and ¹³C NMR or spectroscopic analysis. The results showed a good yielding from 10 . It is noteworthy that the reagents used in this investigation are not expensive and do not require special conditions for handling.     

A new and highly effective organometallic approach to 1,2-dehalogenations and related reactions

We investigated the reductive elimination of several functionalized and non-functionalized vic-dibromides with 1,2-diphenyl-, 1,1,2,2-tetraphenyl- and 1-phenyl-2-(2-pyridyl)-1,2-disodioethane. The reaction, involving some of the less expensive organic and inorganic reagents, proceeds under mild conditions, and is tolerant of a variety of functional groups. Extension of this procedure to similar 1,2-disubstituted compounds was also investigated. Reductive eliminations run on stereochemical probe compounds strongly suggest that this reaction proceeds via a “single electron” reductive elimination reaction pathway.     

Palladium-catalyzed, direct boronic acid synthesis from aryl chlorides: a simplified route to diverse boronate ester derivatives

Although much current research focuses on developing new boron reagents and identifying robust catalytic systems for the cross-coupling of these reagents, the fundamental preparations of the nucleophilic partners (i.e., boronic acids and derivatives) has been studied to a lesser extent. Most current methods to access boronic acids are indirect and require harsh conditions or expensive reagents. A simple and efficient palladium-catalyzed, direct synthesis of arylboronic acids from the corresponding aryl chlorides using an underutilized reagent, tetrahydroxydiboron B(2)(OH)(4), is reported. To ensure preservation of the carbon-boron bond, the boronic acids were efficiently converted to the trifluoroborate derivatives in good to excellent yields without the use of a workup or isolation. Further, the intermediate boronic acids can be easily converted to a wide range of useful boronates. Finally, a two-step, one-pot method was developed to couple two aryl chlorides efficiently in a Suzuki-Miyaura-type reaction.     

New stereoselective beta-C-glycosidation by uncatalyzed 1,4-addition of organolithium reagents to a glycal-derived vinyl oxirane

[reaction: see text] Epoxide 4 is generated in situ from d-glucal-derived hydroxy mesylate 3. Reaction of epoxide 4 with a series of alkyl- and aryllithium reagents affords 2,3-unsaturated beta-C-glycosides with excellent 1,4-regioselectivity and complete stereoselectivity for the beta-glycoside. Other organometallic reagents demonstrate more complex behavior in their reactions with epoxide 4.     

Transformations of several monoterpenoids in the presence of aldehydes in supercritical solvents

The reactivity of verbenol epoxide and isopulegol in supercritical solvents in the presence of aromatic aldehydes was studied using a flow type reactor and a heterogeneous catalyst (Al₂O₃) or no catalyst. The intramolecular transformations or interactions of reagents with the solvent prevailed in all cases; the yield of the products of intermolecular reactions of terpenoids with aldehydes was up to 1%. The aldehydes did not interact with verbenol epoxide but produced a considerable effect on the distribution of its isomerization products.     

Studies on O-,N-Acylation of 3-Hydroxyisoxazole and Their Regioselective Synthesis(Ⅰ)——O-,N-acylation of 5-Methyl-3-hydroxyisoxazole with 2,2-Dimethyl 3-Substituted Cyclopropanecarboxylic Chlorides

The reactions of 5-methyl-3-hydroxyisoxazole with 2, 2-dimethyl, 3-substituted cyclopropanecarboxylic chlorides give O-acyl-5-methyl-3-hydroxyisoxazole and N-acyl-5-methylisoxazolin-3-one derivatives. The ratio of O-acyl to N-acyl product depends upon the acylation reagents. O-acyl derivatives can be converted to the N-acyl compounds by isomerization under acidic conditions or heating.     

Intramolecular aminolysis of trichloroethyl esters: a mild macrocyclization protocol for the preparation of cryptophycin derivatives

The bifunctional catalyst 2-hydroxypyridine (2-pyridone) is shown to promote the intramolecular aminolysis of the polyfunctionalized long-chain amino trichloroethyl ester 8 to afford cryptophycin-51 (4). This process for the construction of the macrocyclic core of cryptophycin derivatives is noteworthy for its convenience, avoidance of expensive coupling reagents, and use of mild reaction conditions.     

Selective iron-catalyzed cross-coupling reactions of grignard reagents with enol triflates, acid chlorides, and dichloroarenes

Cheap, readily available, air stable, nontoxic, and environmentally benign iron salts such as Fe(acac)(3) are excellent precatalysts for the cross-coupling of Grignard reagents with alkenyl triflates and acid chlorides. Moreover, it is shown that dichloroarene and -heteroarene derivatives as the substrates can be selectively monoalkylated by this method. All cross-coupling reactions proceed very rapidly under notably mild conditions and turned out to be compatible with a variety of functional groups in both reaction partners. A detailed analysis of the preparative results suggests that iron-catalyzed C-C bond formations can occur via different pathways. Thus, it is likely that reactions of methylmagnesium halides involve iron-ate complexes as the active components, whereas reactions of Grignard reagents with two or more carbon atoms are effected by highly reduced iron-clusters of the formal composition [Fe(MgX)(2)](n) generated in situ. Control experiments using the ate-complex [Me(4)Fe]Li(2) corroborate this interpretation.     

Designed synthesis of new ortho-carborane derivatives: from mono- to polysubstituted frameworks

The use of nucleophilic and electrophilic processes allow the designed synthesis of several B-iodinated derivatives of o-carborane. Because of the straightforward Pd-catalyzed conversion of B-I to B-C bond with Grignard reagents, such as methylMgBr and biPhenylMgBr, both, symmetrical 3,6-R 2-1,2- closo-C 2B 10H 10 and asymmetrical 3-I-6-Me-1,2- closo-C 2B 10H 10 could be obtained. Not only conventional reactions in solution have been studied but also a highly efficient, clean and fast solvent-free procedure has provided successful results to regioselectively produce B-iodinated o-carborane derivatives by a careful control of the reaction conditions. The high number of nonequivalent leaving groups in boron iodinated o-carborane derivatives opens the possibility through B-C coupling to materials with novel possibilities and to self-assembling due to the enhanced polarizability of the C-H bond.     

Convenient syntheses of novel 1-isothiocyano-alkylphosphonate diphenyl ester derivatives with potential biological activity

Herein, we describe a convenient method for the syntheses of novel 1-isothiocyano-alkylphosphonate diaryl ester derivatives and their antiproliferative activity. The syntheses are based on dithiocarbamates obtained in situ with the use of carbon disulfide under basic conditions, and their desulfurization using several different reagents, of which hydrogen peroxide proved to be the most efficient. The compounds synthesized demonstrated high antiproliferative activity against several cancer cell lines in vitro, and also showed some activity as serine protease inhibitors.