- The carbene fragmentation - Ring expansion route to bridgehead carbocations
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(Matrix Presented) The products, kinetics, and activation parameters were determined for the fragmentation-ring expansions of 1-norbornylmethyloxychlorocarbene (11) and 3-noradamantylmethyloxychlorocarbene (17). Products from 11 (in dichloroethane) included 1-chlorobicyclo[2.2.2]octane (9, 56%) and 1-chlorobicyclo[3.2.1]octane (10, 37%); from 17, we obtained 1-chloroadamantane (15, 68%) and protoadamantyl chloride (16, 28%).
- Moss, Robert A.,Zheng, Fengmei,Fede, Jean-Marie,Sauers, Ronald R.
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- Intramolecular C-H Amination Reaction Provides Direct Access to 1,2-Disubstituted Diamondoids
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We present a new approach to disubstituted diamondoids from corresponding carboxylic acids. A dirhodium-acetate-catalyzed (1 mol-%) nitrene insertion reaction of sulfamides was, for the first time, applied to intramolecular C-H functionalization reactions of rigid tricyclic frameworks. This straightforward approach enables the effective and regioselective synthesis of a variety of diamondoid-based cyclic sulfamidates, which are synthetically valuable building blocks. Reductive deprotection of the sulfamidate moiety leads to corresponding 1,3-amino alcohol derivatives. Oxidation of the sulfamidate moiety by KMnO4 provides access to 1,3-keto alcohols or imines. Finally, we report the synthesis of Vildagliptin analogues as new antidiabetic drug candidates (DPP-4 inhibitors). Intramolecular dirhodium-acetate-catalyzed (1 mol-%) nitrene insertion reactions provide direct access to 1,2-disubstituted diamondoids. This approach was applied to the synthesis of Vildagliptin (DPP-4 inhibitor) analogues.
- Hrdina, Radim,Metz, Fabian M.,Larrosa, Marta,Berndt, Jan-Philipp,Zhygadlo, Yevgeniya Y.,Becker, Sabine,Becker, Jonathan
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- -Rearrangement of iminium salts provides access to heterocycles with adamantane scaffold
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We describe a Br?nsted acid-catalysed cascade reaction consisting of a Wagner-Meerwein rearrangement and a subsequent intra- or intermolecular Friedel-Crafts reaction leading to adamantane-based heterocycles. In contrast to the reported W.-M. rearrangements, in this case an iminium moiety serves as the acceptor of a migrating nucleophilic alkyl group in a [1,2]-alkyl shift. This journal is
- Becker, Jonathan,Duman, Ediz,Hausmann, Heike,Hrdina, Radim,Zonker, Benjamin
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- Experimental and Computational Mechanistic Investigation of Chlorocarbene Additions to Bridgehead Carbene-Anti-Bredt Systems: Noradamantylcarbene-Adamantene and Adamantylcarbene-Homoadamantene
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Cophotolysis of noradamantyldiazirine with the phenanthride precursor of dichlorocarbene or phenylchlorodiazirine in pentane at room temperature produces noradamantylethylenes in 11% yield with slight diastereoselectivity. Cophotolysis of adamantyldiazirine with phenylchlorodiazirine in pentane at room temperature generates adamantylethylenes in 6% yield with no diastereoselectivity. 1H NMR showed the reaction of noradamantyldiazirine + phenylchlorodiazirine to be independent of solvent, and the rate of noradamantyldiazirine consumption correlated with the rate of ethylene formation. Laser flash photolysis showed that reaction of phenylchlorocarbene + adamantene was independent of adamantene concentration. The reaction of phenylchlorocarbene + homoadamantene produces the ethylene products with k = 9.6 × 105 M-1 s-1. Calculations at the UB3LYP/6-31+G(d,p) and UM062X/6-31+G(d,p)//UB3LYP/6-31+G(d,p) levels show the formation of exocyclic ethylenes to proceed (a) on the singlet surface via stepwise addition of phenylchlorocarbene (PhCCl) to bridgehead alkenes adamantene and homoadamantene, respectively, producing an intermediate singlet diradical in each case, or (b) via addition of PhCCl to the diazo analogues of noradamantyl- and adamantyldiazirine. Preliminary direct dynamics calculations on adamantene + PhCCl show a high degree of recrossing (68%), indicative of a flat transition state surface. Overall, 9% of the total trajectories formed noradamantylethylene product, each proceeding via the computed singlet diradical.
- Hare, Stephanie R.,Orman, Marina,Dewan, Faizunnahar,Dalchand, Elizabeth,Buzard, Camilla,Ahmed, Sadia,Tolentino, Julia C.,Sethi, Ulweena,Terlizzi, Kelly,Houferak, Camille,Stein, Aliza M.,Stedronsky, Alexandra,Thamattoor, Dasan M.,Tantillo, Dean J.,Merrer, Dina C.
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p. 5049 - 5065
(2015/06/02)
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- Discovery of adamantane based highly potent HDAC inhibitors
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Herein, we report the development of highly potent HDAC inhibitors for the treatment of cancer. A series of adamantane and nor-adamantane based HDAC inhibitors were designed, synthesized and screened for the inhibitory activity of HDAC. A number of compounds exhibited GI50 of 10-100 nM in human HCT116, NCI-H460 and U251 cancer cells, in vitro. Compound 32 displays efficacy in human tumour animal xenograft model.
- Gopalan, Balasubramanian,Ponpandian, Thanasekaran,Kachhadia, Virendra,Bharathimohan, Kuppusamy,Vignesh, Radhakrishnan,Sivasudar, Velaiah,Narayanan, Shridhar,Mandar, Bhonde,Praveen, Rajendran,Saranya, Nithyanandan,Rajagopal, Sriram,Rajagopal, Sridharan
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p. 2532 - 2537
(2013/06/27)
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- HISTONE DEACETYLASE INHIBITORS FOR THE TREATMENT OF FUNGAL INFECTIONS
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Described are bridged compounds of the formula (I), their analogs, tautomeric forms, stereoisomers, geometrical isomers, polymorphs, hydrates, solvates, pharmaceutically acceptable salts, pharmaceutical compositions, metabolites and prodrugs thereof. The invention relates to compositions and methods to treat fungal infection. These compounds are selective HDAC inhibitors that act as inherent antifungal compounds or enhance the activity of other antifungal compounds such as azoles.
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- Solvent-equilibrated ion pairs from carbene fragmentation reactions
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[R+ OC Cl-] ion pairs were generated in methanol/dichloroethane solutions, with R+ as the 1-bicyclo[2.2.2]octyl, 1-adamantyl, or 3-homoadamantyl cation. Ion pairs were produced either by the direct fragmentation of alkoxychlorocarbenes (ROCCl), with R = 1-bicyclo[2.2.2]octyl, 1-adamantyl, or 3-homoadamantyl, or by the ring expansion-fragmentation of R′CH2OCCl, with R′ = 1-norbornyl, 3-noradamantyl, or 1-adamantyl. Correlations of the [ROMe]/[RCl] product ratios as a function of the mole fraction of MeOH in dichloroethane showed that the homoadamantyl chloride ion pairs, produced by either the direct or ring expansion-fragmentations, were identical, solvent- and anion -equilibrated, and precursor independent. Laser flash photolysis experiments gave 20-30 ps as the time required for solvent equilibration and precursor independence. Methanol/chloride selectivities of the (less-stable) 1-adamantyl chloride and 1-bicyclo[2.2.2]octyl chloride ion pairs were not independent of their ROCCl or R′CH2OCCl precursors. Computational studies provided transition states for the fragmentations and for the structures of the ion pairs.
- Moss, Robert A.,Zheng, Fengmei,Fede, Jean-Marie,Johnson, Lauren A.,Sauers, Ronald R.
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p. 12421 - 12431
(2007/10/03)
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- Rearrangement of 1-noradamantyl and 1-adamantylcarbene to bridgehead alkenes: Lifetimes of two bridgehead carbenes in solution
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B3LYP density functional calculations with the 6-31G* basis set predict that 3-noradamantylcarbene 7 rearranges to adamantene 9 and protoadmant-3-ene 10 over barriers of 0.35 and 7.84 kcal/mol, respectively, after zero-point energy correction. The same level of theory predicts that 1-adamantylcarbene 8 rearranges to homoadamantene 11 over a barrier of 6.06 kcal/mol after zero-point energy correction. To test these predictions, the photochemistry of 3-noradamantyldiazirine 5 and 1-adamantyldiazirine 6 was studied. Photolysis of 5 and 6 in cyclohexane produces the known dimers of the strained alkenes. 1-Adamantylcarbene 8 can be trapped in solution with cyclohexane and piperidine. 1-Adamantylcarbene 8 can be trapped with pyridine to form an ylide upon laser flash photolysis (LFP) of 6. 3-Noradamantylcarbene 7 cannot be intercepted with pyridine in LFP experiments. 3-Noradamantylcarbene 7 is not trapped with cyclohexane and is trapped with piperidine in only miniscule yield. The data indicates that 1-adamantylcarbene 8 is formed more efficiently from its diazirine precursor than is 3-noradamantylcarbene 7 and that the solution-phase lifetime of 1-adamantylcarbene 8 is at least 10 times longer than that of 3-noradamantylcarbene 7.
- Tae, Eunju Lee,Ventre, Celine,Zhu, Zhendong,Likhotvorik, Igor,Ford, Francis,Tippmann, Eric,Platz, Matthew S.
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p. 10146 - 10154
(2007/10/03)
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- Generation and reactivity of 2-substituted adamantenes
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The title bridgehead olefins, generated by the dehalogenation of 1,2- dihalo-2-R-adamantanes (R = Me, Et, Ph, p-CF3C6H4) with excess t-BuLi, yielded 2-t-butyl-2-R-adamantanes (15), 1-t-butyl-2-R-adamantanes (16), and dimeric products. The ratios of the yields (%) of 16 to 15 were 20:3 (R = Me), 32: 3C6H4). 2- Alkyladamantenes predominantly yielded the products t-butylated at C(1), whereas 2-aryladamantenes gave the products t-butylated at C(2). The total yields of the dimers decreased with the bulkiness of substituents at position C(2). The dimerization of 2-methyladamantene gave a head-to-head dimer, 1- (2-methyl-1-adamantyl)-2-methyleneadamantane, as well as a head-to-tail dimer, 1-(2-methyl-2-adamantyl)-2-methyleneadamantane. The [4+2] cycloaddition between two molecules of 2-phenyladamantene, in which the phenyl group participates as a part of the diene, yielded a dimer of the head-to-tail type. These results suggest that: i) a substituent at position C(2) can kinetically stabilize 2-R-adamantene and suppress the dimerization, ii) 2-alkyladamantenes might have a biradical nature, and iii) the regioselective [4+2] cycloaddition and t-BuLi addition of 2-phenyladamantene in THF can be explained by assuming a certain contribution of zwitterionic nature in the double bond that may be dependent on the media and nucleophiles.
- Okazaki, Takao,Tokunaga, Kazuhiko,Kitagawa, Toshikazu,Takeuchi, Ken'ichi
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p. 549 - 561
(2007/10/03)
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- Radical Rearrangements for the Chemical Vapor Deposition of Diamond
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A combination of chemical trapping and computations is used to determine the activation parameters for the interconversion of the 3-methylenebicyclo[3.3.1]nonan-7-yl (1), (3-noradamantyl)methyl (2), and 1-adamantyl (3) radicals. The three radicals model proposed intermediate surface radical structures in the chemical vapor deposition (CVD) of diamond on its 2 × 1 reconstructed [100] surface. The study finds that relatively low-level calculations previously applied to the problem of diamond growth are reliable, at least qualitatively.
- Mueller, Andreas M.,Chen, Peter
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p. 4581 - 4586
(2007/10/03)
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