Ruthenium- and platinum-catalyzed sequential reactions: selective synthesis of fused polycyclic compounds from propargylic alcohols and alkenes

A simple method for the preparation of fused polycyclic compounds by an intramolecular cyclization of propargylic alcohols bearing an alkene moiety at a suitable position has been developed, where the presence of both Ru and Pt catalysts promotes a sequence of catalytic cycles in the same medium. This sequential system can be applied to an intermolecular reaction between a propargylic alcohol and an alkene to obtain the corresponding bicyclo[3,1,0]hex-2-ene derivative. These sequential reactions provide a conceptually new type of cycloaddition system between propargylic alcohols and alkenes.     

Synthesis, reactions, and applications of fluorine-containing multifunctional carbon compounds

The chemistry of compounds containing a carbon atom bearing three or four different labile functional groups has received little attention. These compounds should be of considerable significance in theoretical and synthetic organic chemistry. Among the compounds with multifunctional structures, those having both carbonyl and halogen groups in addition to other heteroatom groups seem especially valuable from a synthetic viewpoint. Their potential use as probes in pure and applied synthetic chemistry has not been exploited, presumably because of structural instability and a paucity of synthetic approaches. Keeping this background in mind, we focused on the synthesis of a new class of multifunctional carbon compounds in which ester carbonyl, halogen, and other heteroatom-derived functional groups are directly attached to the central carbon atom. Fluorine was chosen as the halogen because of the inherent stability of the CF bond and because of the fundamental chemical and biological interest in fluorine-containing compounds. The synthesis, reactions, and some applications of various fluorine-containing multifunctional carbon compounds are described.     

Base-promoted reactions of dichlorocarbene adducts of cyclic enamines: a new route to annulated pyrroles

Treatment of the gem-dihalogenocyclopropanes 1-5 with potassium tert-butoxide or LDA results in the formation of the corresponding and annulated pyrroles 13-17, respectively.     

Synthetic approaches to fused heteroaromatic compounds by the condensation reactions of functional pyrroles

Condensation reactions ol the “functionalized” pyrroles which were obtained by one pot synthesis of aziridines and acetylenic dipolarophiles were discussed. On treatments of 3,4-di- and 2,3,4-tribenzoylpyrroles with hydrazine hydrate and phosphorus pentasulfide, the several pyrrolo-pyridazine derivatives and fused thiophenes, respectively, were prepared. The structure proofs for the products of the reaction of the 2,3,4-tribenzoylpyrrole ( 9a ) with hydrazine hydrate were based on the ¹³C FT-nmr spectrum of the corresponding ¹³C-enriched compounds.     

Syntheses and reactions of some 2,3-disubstituted pyrazine monoxides

The reactions of 2,3-dimethyl- ( 4 ), 2,3-diphenyl- ( 6 ), and 2-methyl-3-phenyl-pyrazine monoxides ( 8 and 9 ) with phosphoryl chloride and acetic anhydride resulted in giving monochloro- and monacetoxy-pyrazines in almost all cases. However, the reaction of 6 with acetic anhydride afforded exceptionally a diacetoxydihydro-pyrazine. These products were converted further to hydroxy or dichloro derivatives.     

Triplex catalyzed diels-alder reactions: Addition of indene to 1,3-cyclohexadiene

The [4+2] cycloaddition (Diels-Alder reaction) of 1,3-cyclohexadiene (CHD) to indene (In) is catalyzed by the singlet excited state of cyanoarenes such as 1,4-dicyanonaphthalene (DCN) and 9,10-dicyanoanthracene (DCA).     

Anthranilic acid hydrazide in the synthesis of fused polycyclic compounds with quinazoline moieties

A modified procedure was developed for the synthesis of 5,6,7,8,13,13a-hexahydrophthalazino[1,2-b]quinazoline-5,8-dione and 6-amino-5,6,6a,11-tetrahydroisoindolo[2,1-a]quinazoline-5,11-dione from o-formylbenzoic acid and anthranilic acid hydrazide. The mechanism of the transformation is suggested, some reactions were studied, and new derivatives of these compounds were synthesized. Anthranilic acid hydrazide was used in the novel synthesis of 5-substituted phthalazino[1,2-b]quinazolin-8-one derivatives. The possible reaction mechanism is discussed. 5,6,7,8-Tetrahydrophthalazino[1,2-b]quinazoline-5,8-dione and 5-phenylphthalazino[2,1-b]quinazolin-8-one were studied by X-ray diffraction.     

Recent advances in the synthesis of benzo[b]thiophene fused polycyclic derivatives: Strategies and reactions

Benzo[b]thiophene fused compounds with a unique active heterocyclic skeleton have wide applications in the fields of medicinal chemistry, organic synthesis, and organic functional materials, which resulted in rapid development of many efficient methods for the construction of benzo[b]thiophene-fused heterocycles in recent years. Among these methods, the domino reaction of benzo[b]thiophene derivatives is a practical and powerful synthetic route to access benzo[b]thiophene-fused heterocycles by virtue of the particularity of sulfur atom. This review summarizes the latest developments in the construction of benzo[b]thiophene-fused heterocycles by ring formation at the C2-C3-position of benzo[b]thiophene derivatives in the past decade. Additionally, this review is divided into four parts according to the four kinds of benzo[b]thiophene derivatives used, including thioaurone, thioisatin, substituted benzo[b]thiophene, and azadiene.     

Syntheses and reactivity of novel unsaturated cyclic compounds containing phosphorus atoms

Kinetic stabilization of compounds containing heavy main-group elements through the use of bulky substituents is of current interest. The widely used 2,4,6-tri-t-butylphenyl group (Mes*) is recognized as a powerful bulky protecting group and has enabled us to successfully prepare various types of phosphorus compounds with unusual structures. When a phosphaalkyne carrying Mes* was treated with tBuLi and then quenched with MeOH, a 1,3-diphosphacyclobutene was obtained, whereas, when MeI was used as a quencher, a 1,3-diphosphacyclobutane-2,4-diyl was formed almost quantitatively as a stable biradical compound. The reaction mechanism for the formation of both compounds can be explained by a phosphide intermediate, which can be formed via dimerization of the phosphaalkyne promoted by tBuLi. Some other diphosphacyclobutane-2,4-diyls with various substituents were prepared in a similar fashion and showed interesting reactivities including ring expansion, oxidation, isomerization and so on.     

Synthesis of pyridine fused polycyclic amines using sequential ring-closing metathesis and radical cyclisation reactions

The syntheses of novel pyridine fused polycyclic bridgehead amines are described using sequential ring-closing metathesis (RCM) and 5-exo-trig intramolecular radical cyclisation reactions. Critical to the success of the two sequential steps were the RCM catalyst and/or the nature of the nitrogen atom.     

Syntheses, structures and reactions of a series of beta-diketiminatoyttrium compounds

This paper describes the synthesis and selected reactions of a series of crystalline mono(beta-diiminato)yttrium chlorides , , , , , , and . The X-ray structure of each has been determined, as well as of [YCl()(2)] (), [Y()(2)OBu(t)] () and [Y{CH(SiMe(3))(2)}(thf)(mu-Cl)(2)Li(OEt(2))(2)(mu-Cl)](2) (). The N,N'-kappa(2)-beta-diiminato ligands were [{N(R)C(Me)}(2)CH](-) [R = C(6)H(4)Pr(i)-2 (); R = C(6)H(4)Bu(t)-2 (); R = C(6)H(3)Pr(i)(2)-2,6 ()], [{N(SiMe(3))C(Ph)}(2)CH)](-) () and [{N(C(6)H(3)Pr(i)(2)-2,6)C(H)}(2)CPh](-) (). Equivalent portions of Li[L(x)] and YCl(3) in Et(2)O under mild conditions yielded [Y(mu-Cl)(L(x))(mu-Cl)(2)Li(OEt(2))(2)](2) [L(x) = () or ()] and [Y(mu-Cl)()(mu-Cl)Li(OEt(2))(2)(mu-Cl)](2) () or its thf (instead of Et(2)O) equivalent . Each of the Li(OEt(2))(2)Cl(2) moieties is bonded in a terminal () or bridging () mode with respect to the two Y atoms; the difference is attributed to the greater steric demand of than or . Under slightly more forcing conditions, YCl(3) and Li() (via) gave the lithium-free complex [YCl(2)()(thf)(2)] (). Two isoleptic compounds and (having in place of in , and , respectively) were obtained from YCl(3) and an equivalent portion of K[] and Na[], respectively; under the same conditions using Na[], the unexpected product was [YCl()(2)] () (i.e. incorporating only one half of the YCl(3)). A further unusual outcome was in the formation of from and 2 Li[CH(SiMe(3))(2)]. Compound [Y(){N(H)C(6)H(3)Pr(i)(2)-2,6}(thf)(mu(3)-Cl)(2)K](2).4Et(2)O (), obtained from and K[N(H)C(6)H(3)Pr(i)(2)-2,6], is noteworthy among group 3 or lanthanide metal (M) compounds for containing MClKCl (M = Y) moieties.     

Redox reactions of hydrogen adducts of thymine: Comparisons with the reactions of hydroxyl adducts

Hydrogen atoms form two kinds of adducts with thymine (oxidizing and reducing). Redox reactions of these two kinds, popularly known as 5-hydrogenated-6-thyminyl (reducing) and 6-hydrogenated-5-thyminyl (oxidizing), were investigated where ferric ions (oxidizing) and ferrous ions (reducing) were used as the corresponding redox partners. A steady-state gamma radiolytic system was chosen where hydroxyl radicals were scavenged using t-butyl alcohol in acidic (pH 1.8) solution. It is inferred that the redox potential of oxidizing hydrogenated thyminyl radicals lies between 0.77 and 1.4 V vs. NHE. The reducing hydrogenated thyminyl radical has a redox value less than 0.8 V because it efficiently undergoes electron transfer reaction with Fe(III). A probable range of redox values for hydroxyl adduct of thymine is included for comparison.     

Understanding the domino reactions of alkyne-tethered N-tosylhydrazones yielding fused polycyclic pyrazoles. An MEDT study

The domino reactions of alkyne-tethered N-mesylhydrazones yielding fused polycyclic pyrazoles have been studied within the Molecular Electron Density Theory (MEDT). Analysis of the Gibbs free energies indicates that the more favourable reactive path is the one in which the elimination of mesylate anion takes place before the intramolecular [3 + 2] cycloaddition (IM32CA) reaction, which corresponds with the rate-determining step of these domino processes. ELF topological analysis of the bond formation along the IM32CA reaction indicates that in spite of the high activation energy associated to this intramolecular reaction, it shows a pmr-type mechanism characterised by the presence of a pseudoradical carbon at the phenyldiazomethane framework.     

Syntheses and reactions of some fluorinated dienes,cyclobutenes and furans

There are many reports¹ of the pyrolysis of fluorinated organic compounds, including the defluorination of cyclic fluorocarbons over iron to give aromatic compounds. Extending this technique we have investigated the flow pyrolysis of some readily accessible unsaturated fluorocarbons, such as I, II, and III, and found these to be synthetically

useful routes to fluorinated dienes, cyclobutenes, and furans. Pyrolyses were carried out using a nitrogen flow over platinum, iron or caesium fluoride heated at 430–700°. The various products can all be rationalized in terms of intermediate allylic radicals, and the solid substrate influences which allylic radicals are formed.We are also investigating the chemistry of those now accessible compounds, such as IV, V, and VI, and some of the preliminary results are described.

For example the fluoride ion induced dimerisation of IV gave two major products VII and VIII via a particular interesting mechanism.

     

Identification of some polycyclic nitrogen-containing compounds in coal-derived oil

A systematic method for the identification of aza-arenes in coal-derived oil was developed. The basic nitrogen-containing substances were extracted with 6 M hydrochloric acid and fractionated sequentially by using gel chromatography and thin-layer chromatography (TLC) on an alumina plate. The aza-arenes in these fractions were separated by using glass capillary gas chromatography. Individual compounds in the column effluent were trapped in a system consisting of a valve for flow switching and a trapping tube made from a glass capillary. The fluorescence spectra of nanogram to subnanogram amounts of trapped compounds were measured. Some attempts were made to identify components based on their TLC RF values and their fluorescence spectra, in addition to their mass spectra.     

Synthesis of 2-arylhydrazones of aliphatic fluorine-containing 1,2,3-tricarbonyl compounds and their reactions with dinucleophiles

New fluorinated 2-arylhydrazones of 1,2,3-tricarbonyl compounds were obtained by coupling fluorine-containing 3-oxo esters, 1,3-diketones, and their copper chelates with aryldiazonium chlorides. Reactions of these arylhydrazones with hydrazine hydrate, phenylhydrazine, thiosemicarbazide, and hydroxylamine gave the corresponding pyrazole and isoxazole derivatives. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 695–700, April, 1998.