Pentasulfide S5(2-) as the first tridentate chelating ligand in Ru(P(OE)3)3S5(E = Me and Et)

Room temperature stirring of H2Ru(P(OE)3)4 (E = Me and Et) and elemental sulfur in benzene afforded the optically active compounds Ru(P(OMe)3)3S5 (1) and Ru(P(OEt)3)3S5 (2). Compounds 1 and 2 are crystallized in the trigonal space group P31 with a = 14.231(10) A, c = 10.24(1) A, V = 1794(2) A3, and Z = 3, and orthorhombic space group P212121 with a = 15.393(5) A, b = 18.126(6) A, c = 12.421(4) A, V = 3465(1) A3, and Z = 4, respectively. Solutions of 1 and 2 did not show any optical activity since the bulk materials are racemic mixtures. The X-ray analyses also reveal that in both compounds polysulfide S5(2-) ion acts as a novel tridentate ligand, resulting in an asymmetric bicyclic RuS5 unit having three- and five-membered rings around the ruthenium atom. Fragmentation of the S5(2-) ring to S2- ion was observed in the presence of sulfur-abstracting reagents such as PR3 (R = Ph, OMe, and OEt) and also to S2(2-) ion when the compounds were reacted with RuCl2(P(OE)3)4 (E = Me and Et).     

Reactions of polyhalopyridines 5. Reaction of 2,3,5,6-tetrachloro-4-trifluoromethylthiopyridine with nucleophilic reagents

The reaction on 2, 3, 3, 6-tetrachloro-4-trifluoromethylthiopyridine with various nucleophilic reagents has been studied. It was shown that the CF₃S group is readily replaced under the action of O- and S-nucleophiles. Competition was detected between replacement of an a-chlorine atom on the pyridine ring and of the fluorinecontaining group under the action of N-nucleophilic reagents. New derivatives of trichlorotrifluoromethylthiopyridine with nitrogen-containing substituents have been synthesized.For Communication 4 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 63–67, January, 1994.     

Reactivity of some 3-substituted-6,8-dimethylchromones toward some nucleophilic reagents

The reactivity of 3-substituted-6,8-dimethylchromone derivatives 1 - 5 was investigated toward selected nucleophilic reagents namely; 3-amino-1,2,4-triazole, 2-aminobenzimidazole, 7-chloro-4-hydrazinoquinoline, and 5,6-diphenyl-3-hydrazino-1,2,4-triazine. These nucleophiles were allowed to react with 6,8-dimethylchromone-3-carboxaldehyde ( 1 ) through condensation with the aldehyde group with opening of γ-pyrone ring giving compounds 6 , 7 , 10, and 11 . Reactions with 6,8-dimethylchromone-3-carbonitrile ( 2 ), and 6,8-dimethylchromone-3-carboxylic acid ( 3 ) occur via attack at position 2 in both compounds followed by cycloaddition onto the nitrile function (in case of carbonitrile 2 ) or decarboxylation and cyclocondensation with the carbonyl group (in case of carboxylic acid 3 ). The current nucleophilic reagents reacted with simple condensation products 4 and 5 , in boiling dioxane, through nucleophilic addition at the exocyclic vinyl bond followed by addition at the CN group giving 6,8-dimethylchromone linked various heterocyclic systems 20 - 27 .     

Copper-catalyzed asymmetric ring opening of oxabicyclic alkenes with organolithium reagents

A highly efficient method is reported for the asymmetric ring opening of oxabicyclic alkenes with organolithium reagents. Using a copper/chiral phosphoramidite complex together with a Lewis acid (BF(3)·OEt(2)), full selectivity for the anti isomer and excellent enantioselectivities were obtained for the ring opened products.     

Regioselective synthesis of pyrimido[1,2-a][1,3,5]triazin-6-ones via reaction of 1-(6-oxo-1,6-dihydropyrimidin-2-yl)guanidines with triethylorthoacetate: observation of an unexpected rearrangement

A novel thermal rearrangement, involving pyrimidine ring opening and subsequent ring closure leading to recyclization of the system, was identified in the reaction of (6-oxo-1,6-dihydropyrimidin-2-yl)guanidines 3 (where NR(1)R(2) = NH(2), NH alkyl, NH aralkyl, NHCH(2)Ph(R)) with triethyl orthoacetate, affording 4-substituted-2-methyl-6H-pyrimido[1,2-a][1,3,5]triazin-6-ones 6 and their ring opened products. However, no such rearrangement was observed with (6-oxo-1,6-dihydropyrimidin-2-yl)guanidines 3 bearing a tertiary amino or anilino substituent (i.e. where NR(1)R(2) = N(CH(3))(2), indoline, morpholino, NHAr). As expected, 2-substituted-4-methyl-6H-pyrimido[1,2-a][1,3,5]triazin-6-ones 4 were obtained as the final products. Experimental structural determination and theoretical studies were carried out to get an understanding of the observed thermal rearrangement. In addition, an attempt to obtain similar pyrimido[1,2-a][1,3,5]triazin-6-ones using N,N-dimethylacetamide dimethyl acetal (DMA-DMA) as one carbon inserting synthon had furnished triazine ring annulated product 14 bearing N,N-dimethyl enamino substituent at position 4 as a result of further reaction with a second molecule of DMA-DMA.     

Tautomeric Equilibrium in Sulfo Derivatives of 4-(Phenylazo)-1-Naphthol in Micellar Solutions of Nonionic Surfactants

Two reagents of the 4-(phenylazo)-1-naphthol series were synthesized: 4-(4-sulfobenzeneazo)-1-naphthol-2-sulfonic acid (SBANS) and 4-(benzeneazo)-1-naphthol-2-sulfonic acid (BANS). These reagents contain the sulfo group at the ortho position with respect to the hydroxy group in the naphthol ring and differ by the presence or the absence of one more sulfo group at the para position in the benzene ring. The effect of ethanol and micelles of three types of nonionic surfactants (Proxamine-385, Brij-35, and Triton X-100) on the azo–quinonehydrazone tautomerism of BANS, SBANS, and their analogue Tropaeolin 000 was studied. It was demonstrated that an increase in the concentration of ethanol or the solubilization of the reagents in the micelles of nonionic surfactants shifts the tautomeric equilibrium to the less polar azo form. It was found that the sulfo group in the naphthol ring controls the lability of the tautomeric equilibrium. Tautomeric constants in aqueous–ethanolic solutions and nonionic surfactant micelles were calculated, and the effective dielectric constant of the medium at the position of localization of the reagents in the hydroxyethylene layer of the micelles was estimated using a model approach.     

杂芳基乙烯光化学反应的研究 2: r-1, c-2, t-3, t-4-1, 3-二(4-甲基苯基)-2, 4-二(4-吡啶基)环丁烷的结构及光解反应

通过反-1-(4-甲基苯基)-2-(4-吡啶基)乙烯(E-MEP)在稀盐酸中的光二聚反应得到了接近定量的标题化合物(DMDPC)。用元素分析,IR, UV, 1H NMR和MS表征了其结构, 并用X射线衍射法测定了DMDPC的晶体结构。DMDPC属单斜晶系, 空间群为P21/c, 晶胞参数a=1.1376(6), b=1.7379(8), c=1.1590(5)nm, β=106.16(4)ⅲ, Z=4。由于四元环同侧苯环和吡啶环的相互排斥作用, DMDPC采取蝶式构象。研究发现, DMDPC在短波紫外光照射下易发生开环反应; 同时还发现,E-MEP与其顺式异构体(Z-MEP)间的反-顺异构化平衡受照射光波长控制。     

Investigations on the Reactivity of Fascaplysin,Part II,General Stability Considerations and Products Formed with Nucleophiles

Reversible deprotonation of fascaplysin ( 1 ) was achieved with non‐nucleophilic bases (Scheme 1). Under basic aqueous conditions, opening of ring D of 1 occurred, yielding zwitter‐ionic reticulatine 2a , whereas, in a methoxide‐containing MeOH solution, an unexpected addition of three molecules of MeOH to the pyridinium ring produced an isomer mixture 3 of a trimethoxy‐substituted compound (Scheme 2). Transformation of the keto group of 1 to the oxime 4A took place in the presence of pyridine as base (Scheme 3). Grignard and alkyllithium reagents added as expected to the keto group of 1 , providing tertiary alcohols 5 and 6 (Scheme 4).     

Photophysics of 6-(2′-hydroxy-4′-methoxyphenyl)-s-triazine photostabilizers

The room temperature photophysical properties of several sulphonated and unsulphonated 6-(2′-hydroxy-4′-methoxyphenyl)-s-triazines were investigated in a range of solvents by means of steady state and picosecond fluorescence spectroscopy. Compounds possessing phenyl or p-tolyl groups in the s-triazinyl ring exhibit only a very weak normal Stokes-shifted fluorescence, arising from the initially excited chromophore. Substitution of phenoxy groups into the s-triazinyl ring results in the appearance of an additional longer-wavelength fluorescence which is assigned to the keto tautomer, formed following excited state intramolecular proton transfer (ESIPT). The rate constant for the (ESIPT) process that occurs in sodium 3-(3′,5′-diphenoxy-2′,4′,6′-triazinyl)-4-hydroxy-2-methoxybenzene sulphonate in water is estimated to be greater than 10¹¹ s⁻¹.     

Extending the time: solvothermal syntheses, crystal structures, and properties of two non-isostructural thioantimonates with the composition [Mn(tren)]Sb2S4

The two novel compounds, [Mn(tren)]Sb2S4 (1 and 2), were obtained by the reaction of elemental Mn, Sb, and S in aqueous solutions of tren (tren = tris(2-aminoethyl)amine, C6H18N4) after different reaction times. Compound 1 is formed up to a reaction time of 13 d, and an extension of the reaction time leads to the formation of 2. Both compounds crystallize in monoclinic space groups (1, P2(1)/c; 2, C2/c). In 1, the two unique SbS3 trigonal pyramids share a common S atom to form a Sb2S5 unit. Two S atoms of this group have a bond to Mn2+ yielding a MnSb2S3 heteroring in the boat conformation. The Sb2S5 moieties are joined via common corners into the final undulated [Sb2S4]2- anion which is directed along [001]. The structure of 2 contains the [Mn(tren)]2+ ion, one SbS3 pyramid, and a SbS4 unit. Two symmetry-related SbS4 groups share an edge, forming a Sb2S6 group containing a Sb2S2 ring. This group is joined via corners to two SbS3 pyramids on both sides producing a Sb4S4 ring. The Sb2S2 and Sb4S4 rings are condensed into the final [Sb2S4]2- anion which runs along [010]. The [Mn(tren)] groups are bound to the thioantimonate(III) backbone on opposite sides of the Sb4S4 ring, and a small MnSbS2 ring is formed. In both structures, weak S...H bonds are found which may contribute to the stability of the materials. The two compounds decompose in one step upon heating, and only MnS and Sb2S3 could be identified as the crystalline part of the decomposition products. Both compounds can also be prepared under solvothermal conditions using MnSb2S4 as starting material. Compounds 1 and 2 are obtained from this ternary material in a high yield.     

Crystal Structure of 5-(l-Menthyloxy)-3-Chloro-4-Pyrrolidinyl-2(5H)-Furanone

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Nucleophilic addition to 3‐methyl‐1‐(4‐nitrophenyl)‐2‐phenyl‐4,5‐dihydroimidazolium iodide

Reactions of the 1,2‐diaryl 4,5‐dihydroimidazolium, represented by 3‐methyl‐1‐(4‐nitrophenyl)‐2‐phenyl‐4,5‐dihydroimidazolium iodide 1 , with ethylenediamine afforded a benzylidyne unit transferred product, 2‐phenyl‐2‐imidazoline 2 ; a ring‐opened adduct 4 was produced when excess ethylenediamine was used. Reactions of 1 with hydroxylamine, malononitrile, and nitromethane anions produced ring‐opened products, 5 , 7 , and 8 respectively.     

Novel structural analogs of glyphosate based on azoles. 2*. N-Substituted imidazoles and pyrazoles obtained by alkylation of heterocycles containing carboxyl or phosphoryl groups in the ring

Alkylation of 4(5)-substituted 1H-imidazoles using the corresponding reagents gave imidazole 1,4-isomers containing phosphoryl and carboxyl groups together in the ring and in the alkyl fragment. The alkylation of pyrazoles containing a carboxyl group at positions 3(5) and 4 of the ring using diethyl phosphonomethyltriflate has been studied.     

蒂巴茵衍生物的合成研究

The reaction of 7α-acetyl-6,14-endoethano-6,7,8,14-tetrahydrothebaine with 2-（thien-2-yl）ethylmagnesium bromide was investigated. The tertiary alcohol derivative 7α-[R-l-hydroxyl-l-methyl-3-（thien-2-yl）propyl]）-6,14- endoethano-6,7,8,14-tetrahydrothebaine （3） and a by-product 4 were isolated. The structure of 4 was elucidated by X-ray analysis. The Grignard reaction shows high degree of stereoselectivity according with Cram rule. The crystal structure of 4 indicates that dihydrofuran ring was opened to form a phenolic hydroxyl group and a three-membered ring structure. It maintains the main rigid structure of morphine and contains a C（6）-C（14） enthano bridge. The 1-hydroxyl-1-methyl-3-（thien-2-yl）propyl group at C（7） position adopted S-configuration.     

A new efficient route to chiral 1,3-disubstituted ferrocenes: application to the syntheses of (R(p))- and (S(p))-17alpha-[(3'-formylferrocenyl)ethynyl]estradiol

Starting from (2S,4S)-2-ferrocenyl-4-(methoxymethyl)-1,3-dioxane (4), use of the stereogenic ortho-directing menthyl para-tolyl sulfoxide group, which occupies the 2' position in the ferrocenyl ring and redirects subsequent lithiation to the 3' position, allowed the synthesis of optically pure (S(p))-1-formyl-3-iodoferrocene (8), that was characterized by single-crystal X-ray diffraction. Combination of this method with a protection-deprotection strategy, using trimethylsilyl as a temporary blocking group, yielded (R(p))-1-formyl-3-iodoferrocene (13). Separate Sonogashira coupling of each of the enantiomeric iodoformylferrocenes 8 and 13 with 17alpha-ethynyl-estradiol produced (R(p))-17alpha-[(3'-formylferrocenyl)ethynyl]estradiol (14) and (S(p))-17alpha-[(3'-formylferrocenyl)ethynyl]estradiol (15), respectively.     

A spiro to ansa rearrangement in cyclotriphosphazene derivatives

Nucleophilic substitution reactions of cyclotriphosphazene derivatives having five-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(2)X] (X = NH or O) with alkoxides (of tetraethylene glycol and some mono-functional alcohols) give unexpected rearrangements to form stable seven-membered ring ansa compounds, even though crystallographic evidence shows ring distortion and compression of the cyclophosphazene ring. With weaker nucleophiles such as sodium phenoxide and pyrrolidine substitution at a PCl2 group is preferred and no rearrangement takes place. In contrast, reactions of the analogous phosphazenes containing six-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(3)X], with all of the above reagents give only normal substitution reactions at the PCl2 moieties and no rearrangement products. The spiro to ansa rearrangements in cyclophosphazenes are remarkable as the reported primary reaction products with the same difunctional reagents HO(CH(2))(2)XH are predominantly spiro, with some dangling and bridging derivatives, but no ansa compounds.     

羟甲芬太尼对映异构体的^1H NMR及立体化学

本文对强效镇痛剂羟甲芬太尼(OMF)八个对映异构体中的其中四个, 即(-)-cis-(3R,4S,2'R)-OMF (1), (+)-cis-(3-R,4S,2'S)-OMF (2),(+)-trans-(3S,4S,2'R)-OMF (3), 和(+)-trans-(3S,4S,2'S)-OMF (4)进行了^1HNMR研究, 归属了所有的共振谱线。对哌啶环质子间偶合常数的分析表明, 所有顺式和反式异构体中的哌啶环都呈现相同的椅式构象。在顺式异构体中3-甲基位于直立键, 而4-N-苯基丙酰胺基位于平伏键, 反式异构体中它们均位于平伏键。讨论了3-甲基和4-N-苯基丙酰胺基的立体取代对NMR的影响, 在顺式异构体中4-N-苯基丙酰胺基的构象相对固定, 而在反式异构体中则较为自由。     

Efficient Synthesis of Ephedra Alkaloid Analogues Using an Enantiomerically Pure N-[(R)-(+)-alpha-Methylbenzyl]aziridine-2-carboxaldehyde

Efficient preparation of enantiomerically pure (2S)-aziridine-2-carboxaldehyde 9 and its 2(R) isomer and highly diastereoselective addition of organolithium reagents to the aldehyde 9 are described. The diastereoselectivity in additions of the lithium reagents seems to come from "chelation-controlled" carbon-carbon bond formation and is influenced by the source of the organometallic compound, solvent, and the presence of a Li salt. The C(3)-N bond of the aziridine ring of the addition products was regioselectively reduced by catalytic hydrogenation in the presence of Pearlman's catalyst to provide enantiomerically pure 1,2-amino alcohols. The absolute stereochemistries of the amino alcohol 13a were assigned as (1S,2S) when the C-1 substituent was phenyl by comparison with those of commercially available norpseudoephedrine.     

Acid-, base-, and lewis-acid-catalyzed heterolysis of methoxide from an alpha-hydroxy-beta-methoxy radical: models for reactions catalyzed by coenzyme B12-dependent diol dehydratase

[Reaction: see text].A model for glycol radicals was employed in laser flash photolysis kinetic studies of catalysis of the fragmentation of a methoxy group adjacent to an alpha-hydroxy radical center. Photolysis of a phenylselenylmethylcyclopropane precursor gave a cyclopropylcarbinyl radical that rapidly ring opened to the target alpha-hydroxy-beta-methoxy radical (3). Heterolysis of the methoxy group in 3 gave an enolyl radical (4a) or an enol ether radical cation (4b), depending upon pH. Radicals 4 contain a 2,2-diphenylcyclopropane reporter group, and they rapidly opened to give UV-observable diphenylalkyl radicals as the final products. No heterolysis was observed for radical 3 under neutral conditions. In basic aqueous acetonitrile solutions, specific base catalysis of the heterolysis was observed; the pK(a) of radical 3 was determined to be 12.5 from kinetic titration plots, and the ketyl radical formed by deprotonation of 3 eliminated methoxide with a rate constant of 5 x 10(7) s(-1). In the presence of carboxylic acids in acetonitrile solutions, radical 3 eliminated methanol in a general acid-catalyzed reaction, and rate constants for protonation of the methoxy group in 3 by several acids were measured. Radical 3 also reacted by fragmentation of methoxide in Lewis-acid-catalyzed heterolysis reactions; ZnBr2, Sc(OTf)3, and BF3 were found to be efficient catalysts. Catalytic rate constants for the heterolysis reactions were in the range of 3 x 10(4) to 2 x 10(6) s(-1). The Lewis-acid-catalyzed heterolysis reactions are fast enough for kinetic competence in coenzyme B12 dependent enzyme-catalyzed reactions of glycols, and Lewis-acid-catalyzed cleavages of beta-ethers in radicals might be applied in synthetic reactions.     

Synthesis of the bi-heterocyclic parent ring system 1,2,4-triazolo[4,3-b][1,2,4,5]tetrazine and some 3,6-disubstituted derivatives

The synthesis of the previously unknown parent ring system was developed. Treatment of 3-hydrazino-1,2,4,5-tetrazine ( 4 ) with diethoxymethyl acetate gave the parent ring system. Similar treatment of 3-(3,5-dimethylpyrazol-1-yl)-6-hydrazino-1,2,4,5-tetrazine ( 2 ) with one carbon cyclizing reagents gave 3,6-di-substituted derivatives of the 1,2,4-triazolo-1,2,4,5-tetrazine ring system.