Showing papers on "Aryl radical published in 2000"

Bu3SnH mediated oxidative radical cyclisations: synthesis of 6H-benzo[c]chromen-6-ones

Abstract: Attempts to synthesise 6H-benzo[c]chromen-6-ones by Bu3SnH mediated cyclisation of o-(benzoyl)aryl radicals failed because of the preferred trans conformation of the ester. This problem was overcome by using cyclisation of o-(benzyloxy)aryl and o-[(aryloxy)methyl]aryl radicals to yield 6H-benzo[c]chromenes followed by oxidation to the 6H-benzo[c]chromen-6-ones. 3-Methoxy-6H-benzo[c]chromen-6-one 1, one of the main biologically active constituents of shilajit, a herbal medicine used in countries surrounding the Himalayan mountains, was synthesised using Bu3SnH mediated cyclisation of 1-benzyloxy-2,4-dibromo-5-methoxybenzene 31 to yield 3-methoxy-6H-benzo[c]chromene 25 followed by PCC oxidation of the 6-position. In order to avoid the problems of rearrangement, the aryl radical cyclisation must be designed such that whichever way the spirodienyl intermediate rearranges, the same product is obtained. For instance, the Bu3SnH mediated cyclisation of 1-iodo- and 1-bromo-2-(3-methoxyphenyloxymethyl)benzenes 22 and 23 respectively gave both the isomers, 1-methoxy-6H-benzo[c]chromenes 24 and 3-methoxy-6H-benzo[c]chromenes 25via rearrangement of the intermediate spirodienyl radical. The synthesised 6H-benzo[c]chromenes were oxidised in high yield to the corresponding 6H-benzo[c]chromen-6-ones. The mechanism of the ‘oxidative’ Bu3SnH mediated cyclisation is discussed.

Regiochemistry in Aryl Radical Cyclization onto Methylenecycloalkanes

Abstract: Bu(3)SnH-mediated aryl radical cyclization onto methylenecycloalkanes having a phenylthio, an ester, or a nitrile group at the terminus of the alkenic bond provides exclusively exo cyclization products. The results are in sharp contrast to those reported for nonsubstituted methylenecycloalkanes, which give exclusively endo cyclization products. Formation of endo cyclization products has been suggested to be a result of a consecutive 5-exo cyclization of an aryl radical and neophyl rearrangement. The exo-selective aryl radical cyclization offers a new method for synthesizing fused aromatic compounds containing a benzylic quaternary carbon atom.

Formation pathways of ethynyl-substituted and cyclopenta-fused polycyclic aromatic hydrocarbons

Abstract: Two novel classes of polycyclic aromatic hydrocarbons (PAH), those with ethynyl substituents (ethynyl-PAH) and those with externally fused five-membered rings (cyclopenta-fused PAH or CP-PAH), have recently been identified in the products of a variety of fuels and combustion/pyrolysis environments. However, the recently developed capacity for identifying these compounds has raised new questions about preferential reaction pathways. Specifically, across various fuels and operating conditions, experimentally observed products are (1) CP-PAH, which result from C 2 H 2 addition to an aryl radical, followed by cyclization to a cyclopenta ring and (2) ethynyl-PAH, which result from C 2 H 2 addition to locations on the aryl radical where cyclization is not possible. We have never observed ethynyl-PAH resulting from C 2 H 2 addition to an aryl radical at a point where cyclization into a five-membered ring is possible. To explain this behavior, we have performed AM1 semiempirical quantum chemical computations with group correction in order to examine the potential energy surfaces of the reaction pathways that lead to ethynyl-PAH and CP-PAH. We have performed computations for the parent aryl radical, possible ethynyl-PAH products, possible CP-PAH products, as well as intermediates and transition states, for C 2 H 2 addition to naphthalene, anthracene, phenanthrene, acenaphthylene, fluoranthene, and pyrene. Possible CP-PAH products are acenaphthylene, aceanthrylene, acephenanthrylene, pyracylene, cyclopenta[ cd ]fluoranthene, and cyclopenta[ cd ]pyrene. In all cases, we have found that, although energy differences between ethynyl-PAH isomers are very small (∼1 kcal/mol), the experimentally observed ethynyl-PAH is always the lowest energy isomer. Furthermore, the observed preference for cyclization to CP-PAH over formation of an ethynyl-PAH can be explained by the significantly lower energy barrier (23 vs. 36 kcal/mol) for the cyclization reactions. Finally, we have determined that, while not prohibited, the isomerization of ethynyl-PAH to CP-PAH requires significantly higher energy than the aryl-vinyl cyclization reactions, and therefore is not expected to make a significant contribution to the product distribution. These results are sufficiently consistent that the computation of reaction pathway energy surfaces can be used to identify likely ethynyl-PAH and CP-PAH products from the addition of C 2 H 2 to much larger parent PAH.

Selective metal cation activation of a DNA alkylating agent: synthesis and evaluation of methyl 1,2,9, 9a-Tetrahydrocyclopropa[c]pyrido[3,2-e]indol-4-one-7-carboxylate (CPyI).

Abstract: The synthesis of methyl 1,2,9,9a-tetrahydrocyclopropa[c]pyrido[3,2-e]indol-4-one-7-carboxylate (CPyI) containing a one carbon expansion of the C ring pyrrole found in the duocarmycin SA alkylation subunit and its incorporation into analogues of the natural product are detailed. The unique 8-ketoquinoline structure of CPyI was expected to provide a tunable means to effect activation via selective metal cation complexation. The synthesis of CPyI was based on a modified Skraup quinoline synthesis followed by a 5-exo-trig aryl radical cyclization onto an unactivated alkene with subsequent TEMPO trap or 5-exo-trig aryl radical cyclization onto a vinyl chloride for synthesis of the immediate precursor. Closure of the activated cyclopropane, accomplished by an Ar-3‘ spirocyclization, provided the CPyI nucleus in 10 steps and excellent overall conversion (29%). The evaluation of the CPyI-based agents revealed an intrinsic stability comparable to that of CC-1065 and duocarmycin A but that it is more reactive than ...

Regiochemistry in aryl radical cyclisations (5-exoversus 6-endo) of N-vinylic 2-iodobenzamides

Abstract: Bu3SnH-mediated aryl radical cyclisations of a range of N-vinylic 2-iodobenzamides 10 were examined. The enamides 10a–d gave exclusively the 5-exo cyclisation products 11a–d, whereas the enamides 10e,f having a phenyl substituent on the vinylic carbon atom α to the nitrogen atom gave predominantly the 6-endo cyclisation products 14 and 18, respectively. The experiments on the effect of concentration of Bu3SnH or temperature on the products distribution showed that the formation of the 6-endo cyclisation products 14 and 18 was a result of a 5-exo cyclisation of the aryl radicals formed from 10e,f followed by neophyl rearrangement of the intermediate radicals.

The synthesis of 3-methyleneindol-2(3H)-ones related to mitomycins via 5-exo-dig aryl radical cyclisation

Abstract: The synthesis of acetylenic amides from 2-bromoaniline and propiolic acids followed by their cyclisation via the derived aryl radical is presented. Silylation of the terminal end of the triple bond is shown to be required for successful cyclisation to 3-methyleneindol-2(3H)-ones. The exocyclic double bond can be epoxidised using m-chloroperoxybenzoic acid (MCPBA).

2-Arylimino-2,3-dihydrothiazoles, and their use thereof as somatostatin receptor ligands

Abstract: The invention concerns novel 2-arylimino-2,3-dihydrothiazole derivatives of general formula (I), their preparation methods and their use as medicines, in particular for treating pathological conditions or diseases wherein one (or several) somatostatin receptors is/are involved. Said pathological conditions include in particular acromegaly, pituitary adenoma or endocrine gastroenteropancreatic tumours including the carcinoid syndrome, and gastrointestinal bleeding. In general formula (I), R1 represents in particular an alkyl, aralkyl, cyclohexyl radical optionally substituted by an amino radical or R1 represents a -C(R11)(R12)-CO-R10 radical wherein R11 represents H, R12 represents in particular H, carbocyclic or heterocyclic alkyl, cycloalkyl or aralkyl and R10 represents in particular an aminoalkylamino radical; R2 represents a carcyclic or heterocyclic aryl radical optionally substituted; R3 represents in particular COR5 or a carbocyclic or heterocyclic alkyl, adamantyl, aryl radical optionally substituted, carbocyclic or heterocyclic aralkyl optionally substituted on the aryl group; and R5 represents a radical fixed by a nitrogen atom to the group CO.

Initiator for polymerising and/or cross-linking polyorganosiloxanes with cross-linkable functional groups, corresponding compositions and their uses

Abstract: The invention relates to a heat-activated initiator for polymerising and/or cross-linking polyorganosiloxane-type monomers, oligomers and/or polymers with organofunctional groups, comprising a boron derivative of formula (I): (A)xB(R')y, wherein the symbols R' are the same or different and represent an alkyl or alkenyl radical in C1-C12, an alkoxy radical in C1-C12, a phenyl radical substituted by at least one electroattractor element, an aryl radical containing at least two aromatic rings such as biphenyl, naphthyl, optionally substituted by at least one electroattractor element, especially a halogen atom (particularly fluorine), or an electroattractor group, especially a CF3, NO2, CN group; and a radical -C2H4-Si(Q)3 with the symbols Q being the same or different and representing an alkyl or alkoxy group in C1 to C10 or a siloxane oligomer with less than 10 silicon atoms. The invention also relates to a corresponding cross-linkable composition and to the uses thereof.

Radiolysis of Polyethylene Films Containing Arenes: Bromopyrene Dissociation and Pyrene Binding in Polymer Films

Abstract: Radiation induced dehalogenation of haloarenes and binding of arenes have been studied in polyolefin films. Dehalogenation takes place from a highly excited triplet state that is formed by the recombination of arene radical ions, while binding takes place through a polymer aryl radical intermediate. The latter process is dependent on the reactivity of the polymer radical and decreases in low molecular weight and branched polymer films. It is found that energy deposited by high-energy irradiation is transferred efficiently out of the crystalline zones and into the amorphous zones of the polymer.

Synthesis of benzolactams by 11-endo selective aryl radical cyclisation of 2-iodobenzamides

Abstract: Regioselective 11-endo aryl radical cyclisation of methyl 4-O-allyl-2,3-di-O-benzyl-6-deoxy-6-(2-iodobenzoylamino)-α-D-glucopyranoside 4 and N-(3-allyloxypropyl)-2-iodobenzamide 9 with tri-n-butyltin hydride provided the benzolactams 5 and 10, respectively. The unequivocal structures of 5 and 10 were supported by 1H and 13C NMR spectroscopy and by PENDANT or DEPT, COSY and HMQC experiments.

Clear rinsing agent

Abstract: The use of diquaternary polysiloxanes in detergents for machine dishwashing leads to advantageous effects, especially when the diquaternary polysiloxanes are used in the clear rinsing cycle. Diquaternary polysiloxanes of formula (I) are preferably used in which: Z represents a quaternized nitrogen center; R' and R'', independent of one another, represent a C1-C4- alkyl radical or an aryl radical; M represents a bivalent hydrocarbon radical which has at least 4 carbon atoms, which preferably comprises at least one hydroxy group, and which can be interrupted by one or more oxygen atoms and/or groups of the type -C(O)-, -C(O)O- or -C(O)N-; n represents a number ranging from 1 to 201, and; X- represents an inorganic or organic anion.

Geodesic Polyarenes with Exposed Concave Surfaces

Abstract: Polycyclic aromatic hydrocarbons (PAHs) in which five-membered rings have been interspersed among the six-membered rings generally display curved p systems that can be either fully closed (fullerenes) or partially open (bowl-shaped fullerene fragments), depending on the number of five-membered rings. Both classes of compounds belong to the larger family we call 'GEODESIC POLYARENES.' Herein, we highlight the utility of high temperature aryl radical cyclizations as a general strategy for constructing strained geodesic polyarenes. We also report the first examples of reactions at the 'interior' carbon atoms of neutral PAHs that are not fullerenes, e.g. carbene additions, 1,3-dipolar cycloadditions, osmylation, nucleophilic addition of MeLi, and electrophilic addition of L

Coating film forming material for electrode surface and manufacturing method for battery

Abstract: PROBLEM TO BE SOLVED: To provide an electrolytic solution for lithium ion battery excellent in the thermal stability. SOLUTION: An electrode surface coating film forming material according to the invention contains at least one of the dihalo-dicarbonyl compounds expressed by a formula (I) where X1 and X2 are halogen atoms, R1 and R2 are each alkyl radical, haloalkyl radical, alkoxyalkyl radical, or haloalkoxyalkyl radical of a 1-6C, aryl substituted alkyl radical, or haloaryl substituted alkyl radical of a 7-10C, or aryl radical or haloaryl radical of a 6-10C, and m and n are 0 or 1, and a formula (I') where X1 and X2 are halogen atoms, R3 is alkylene chain or haloalkylene chain of a 1-6C with or without oxygen atom in the chain, and m and n are 0 or 1. COPYRIGHT: (C)2002,JPO

Substituted pyrrole mannich bases to combat pain and allergic reactions

Abstract: The invention relates to substituted pyrrole Mannich bases of general formula (I), wherein R1=H, a C ?1-10?-alkyl-, aryl, a heteroaryl- or an aryl, heteroaryl-, CN, Br-, C1 or OH radical bound by a C 1-6 alkylene group, R?2=CH(R4)N(R5)(R6?), R3, R3', R3'' identically or individually represent H, F, C1, Br, CF?3?, CN, NO2, SO2NH2, NHR?7,SR8, OR9, CO(OR10), CH2CO(OR11), COR15?, a C ?1-10?-alkyl-, aryl-, heteroaryl- aryl radical or a heteroalkyl radical bound by a C 1-6 alkylene group, R?4? = an unsubstituted phenyl radical or a phenyl radical substituted at least with C ?1-4? alkyl, C 1-3-alkoxy-, halogen-, a method for the production of the above-mentioned compounds, medicaments containing said compounds, and the use of said compounds in the production of medicaments. Said active ingredients are particularly suitable for pain therapy, and for treating inflammatory and allergic reactions, drug or alcohol abuse, diarrhoea, gastritis, ulcers, cardiovascular diseases, urinary incontinence, depressions, states of shock, migranes, narcolepsy, overweight, asthma, glaucoma, hyperkinetic syndrome, lack of drive, bulimia, anorexia, catalepsia, anxiolysis, increasing vigilance and/or increasing libido.

Taxoids compound, their preparation and pharmaceutical compositions containing them

Abstract: New taxoids of general formula (I), their preparation and pharmaceutical compositions containing them. In general formula (I), Ar represents an aryl radical, R represents a hydrogen atom or an acetyl, alkoxyacetyl or alkyl radical, R1 represents a benzoyl radical or a radical of formula R2-O-CO- in which R2 represents an optionally substituted alkyl radical, an alkenyl, alkynyl, cycloalkyl, cycloalkenyl, bicycloalkyl, phenyl or heterocyclyl radical. The new products of general formula (I) have a remarkable antitumor activity.

Thermoplastic moulding materials

Abstract: The invention relates to thermoplastic moulding materials containing A) between 10 and 99 % by weight of at least one thermoplastic polymer, B) between 1 and 50 % by weight of a mixture consisting of b1) at least one phosphorous compound and b2) at least one stabiliser compound of the general formulas (I) to (IV) In formula (I), R?1 and R2? represent, independently of one another, a hydrogen radical, a C?1? to C10 alkyl radical, a C6 to C12 aryl radical, a C7 to C13 aralkyl radical, or a C7 to C13 alkylaryl radical, a, b independently of one another, have the values 1 to 5, c, d independently of one another, have the values 0 to 10 In formula (II), R?3? represents a hydrogen radical, a C?1? to C10 alkyl radical, a C6 to C12 aryl radical, a C7 to C13 aralkyl radical, a C7 to C13 alkylaryl radical, e has the value 1 to 4, f has the value 1 to 100 In formula (III), R?4 and R13? independently of one another, represent NCO or NHCOOR', whereby R' represents an alkyl polyetherglycol or an alcohol containing between 1 and 20 C-atoms, R?5, R6, R7, R8, R9, R10, R11, R12? independently of one another, represent a hydrogen radical, a C?1? to C10 alkyl radical, a C6 to C12 aryl radical, a C7 to C13 aralkyl radical, a C7 to C13 alkylaryl radical, g indicates 0 to 5, h indicates 1 to 100 In formula (IV) R?14, R15, R16? independently of one another, represent a hydrogen radical or a radical (a), whereby R17 represents a hydrogen radical, a C?1? to C10 alkyl radical, a C6 to C12 aryl radical, a C7 to C13 aralkyl radical, a C7 to C13 alkylaryl radical, or (CH2)1-N=C=O, whereby 1 indicates 1 to 20, i indicates 2 to 8, j indicates 1 to i-k, k indicates 0 to i-j, whereby j + k ≤ i, or at least two of these groups Said thermoplastic moulding materials also contain C) between 0 and 40 % by weight of a flame-retardant which is different from b1); and D) between 0 and 70 % by weight of additives The weight percentages of components A) to D) always correspond to 100 %

Distinct fragmentation patterns of the radical anions derived from 1-halo-2- and -4-(phenylmethylthio)benzenes

Abstract: Irradiation of 1-bromo-2-[(phenylmethyl)thio]benzene (1), 1-iodo-2-[(phenylmethyl)thio]benzene (2), and 1-iodo-4-[(phenylmethyl)thio]benzene (3), in DMSO as solvent in the presence of pinacolone enolate ion led to entirely different product distributions. Thus, irradiation of 1 afforded exclusively fragmentation of the C–S bond of the thiobenzyl moiety, yielding bibenzyl and 2-bromobenzenethiol, whereas irradiation of 2, under the same reaction conditions, afforded the intramolecularly-cyclized product benzothiochromene (9), which arises from a C–I bond scission.Irradiation of 3, in DMSO as solvent and in the presence of pinacolone enolate ion, afforded p-iodobenzenethiol as the only product under controlled-irradiation conditions.The differences in product distributions upon irradiation of compounds 1, 2, and 3 are ascribed to the different fragmentation rates of the C–X and S–benzyl bonds in the radical anion intermediates which arise from ET reactions from pinacolone enolate ion to the substrates. In this fashion, irradiation of 2 generates a radical anion which readily fragments to iodide ion and the respective aryl radical, which undergoes internal cyclization. Loss of a proton regenerates the radical anion of 9, which in turn transfers the odd electron back to a substrate molecule 2 to continue the chain process. Conversely, the radical anions derived from 1 and 3 fragment into benzyl radicals and the respective sulfides, precluding the chain mechanism.Product quantum yields were determined from irradiation of 1, 2, and 3 in the presence of pinacolone enolate ion, and are in accordance with the mechanisms proposed. p

Rinse aid compositions

Abstract: The use of diquaternary polysiloxanes in detergents for machine dishwashing brings about advantageous effects, especially when the diquaternary polysiloxanes are employed in the rinse cycle. Preferred diquaternary polysiloxanes may be described by the formula I: in which Z is a quaternized nitrogen center, R' and R" independently of one another are a C1-4 alkyl radical or an aryl radical, M is a divalent hydrocarbon radical with at least 4 carbon atoms, which preferably has at least one hydroxyl group and may be interrupted by one or more oxygen atoms and/or groups of the type -C(O)-, -C(O)O- or -C(O)N-, n is a number from 1 to 201, and X- is an organic or inorganic anion.