- Umpolung Strategy for Arene C?H Etherification Leading to Functionalized Chromanes Enabled by I(III) N-Ligated Hypervalent Iodine Reagents
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The direct formation of aryl C?O bonds via the intramolecular dehydrogenative coupling of a C?H bond and a pendant alcohol represents a powerful synthetic transformation. Herein, we report a method for intramolecular arene C?H etherification via an umpoled alcohol cyclization mediated by an I(III) N-HVI reagent. This approach provides access to functionalized chromane scaffolds from primary, secondary and tertiary alcohols via a cascade cyclization-iodonium salt formation, the latter providing a versatile functional handle for downstream derivatization. Computational studies support initial formation of an umpoled O-intermediate via I(III) ligand exchange, followed by competitive direct and spirocyclization/1,2-shift pathways. (Figure presented.).
- Mikhael, Myriam,Guo, Wentao,Tantillo, Dean J.,Wengryniuk, Sarah E.
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supporting information
p. 4867 - 4875
(2021/09/14)
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- INHIBITORS OF NOROVIRUS AND CORONAVIRUS REPLICATION
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Compounds of Formula (I) and methods of inhibiting the replication of viruses in a biological sample or patient, of reducing the amount of viruses in a biological sample or patient, and of treating a virus infection in a patient, comprising administering to said biological sample or patient an effective amount of a compound represented by Formula (I), a compound of Table A or B or a pharmaceutically acceptable salt thereof.
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- A Boron Alkylidene–Alkene Cycloaddition Reaction: Application to the Synthesis of Aphanamal
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We describe an unusual net [2+2] cycloaddition reaction between boron alkylidenes and unactivated alkenes. This reaction provides a new method for the construction of carbocyclic ring systems bearing versatile organoboronic esters. Aside from surveying the scope of this reaction, we provide details about the mechanistic underpinnings of this process, and examine its application to the synthesis of the natural product aphanamal.
- Liu, Xun,Deaton, T. Maxwell,Haeffner, Fredrik,Morken, James P.
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supporting information
p. 11485 - 11489
(2017/09/11)
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- One-pot β-alkylation of secondary alcohols with primary alcohols catalyzed by ruthenacycles
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A ruthenacycle-catalyzed one-pot β-alkylation of secondary alcohols with primary alcohols is described. A survey of four C-N chelate ruthenacycles synthesized via the cyclometallation reaction of phenylmethanamine, N-methylphenylmethanamine, N,N-dimethylphenylmethanamine, and naphthalen-1-ylmethanamine with [(η6-C6H 6)RuCl2]2 was undertaken. All four complexes were found to be active with the phenylmethanamine-based ruthenacycle showing the best combination of reactivity and product selectivity among the four. An expanded scope of substrates was also studied with the inclusion of unsaturated primary alcohols. The reactivity trend observed gave insights into the role of hydrogen bonding in the catalytic mechanism involving transfer hydrogenation between the substrates and the transition metal catalyst.
- Chang, Xu,Chuan, Low Wei,Yongxin, Li,Pullarkat, Sumod A.
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experimental part
p. 1450 - 1455
(2012/04/10)
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- New cyclopentane derivatives as inhibitors of steroid metabolizing enzymes AKR1C1 and AKR1C3
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A series of cyclopentane derivatives was synthesized and evaluated for inhibition of the steroid metabolizing enzymes AKR1C1 and AKR1C3. Selective inhibitors that are active in the low micromolar range were identified. These compounds represent promising starting points in the development of new anticancer agents for the treatment of hormone-dependent forms of cancer and other diseases where AKR1C1 and AKR1C3 are involved.
- Stefane, Bogdan,Brozic, Petra,Vehovc, Matej,Rizner, Tea Lanisnik,Gobec, Stanislav
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experimental part
p. 2563 - 2571
(2009/10/17)
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- Cyclization of 5-hexenyl radicals from nitroxyl radical additions to 4-pentenylketenes and from the acyloin reaction
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Photochemical Wolff rearrangements were used to form 5-substituted-4-pentenylketenes 1a-1d (RCH=CHCH2X-CH 2CH=C=O: 1a R = H, X = CH2; 1b R = Ph, X = CH 2; 1c R = c-Pr, X = CH2; 1d R = H, X = O), which were observed by IR at 2121, 2120, 2119, and 2126 cm-1, respectively, as relatively long-lived species at room temperature in hydrocarbon solvents. These reacted with the nitroxyl radical tetramethylpiperidinyloxyl (TEMPO, TO·) forming carboxy-substituted 5-hexenyl radicals 3, which were trapped by a second nitroxyl radical forming 1,2 diaddition products 4a-4d. On thermolysis, 4a-4d underwent reversible reformation of the radicals 3, which underwent cyclization forming cyclopentanecarboxylic acid derivatives 6 or 11 as the major products. However, in the case of 1b, the cyclopentane derivative was formed reversibly and on prolonged reaction times the only product isolated was PhCH=CH-(CH2)4CO2H (8b) from hydrogen transfer to Cβ and cleavage of the TEMPO group. Cyclopropylcarbinyl radical ring opening in the cyclized radical 5c from 1c led to the 2-(4-N-tetramethylpiperidinyloxybut-1-enyl)cyclopentane derivative 11 as the major product. In a test for 5-hexenyl radical ring closure in the radical anion intermediate of the acyloin condensation, the ester CH 2=CH(CH2)3CO2Et (12a) gave the acyloin 13a (76%) as the only observed product, while PhCH=CH(CH 2)3CO2CH3 (12b) with Na in toluene gave 21% of the acyloin product 13b and 42% of 2-benzylcyclopentanol (15) from cyclization of the intermediate radical anion.
- Henry-Riyad, Huda,Tidwell, Thomas T.
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p. 697 - 704
(2007/10/03)
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- Asymmetric reduction of prochiral cycloalkenones. The influence of exocyclic alkene geometry
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The asymmetric reduction of a series of prochiral enones of general structure 1 using the Corey oxazaborolidine 2, leading to enantiomerically enriched allylic cycloalkanols 3 is described. The influence of alkene geometry on both the sense (R vs. S) and
- Simpson, Alison F.,Bodkin, Corinna D.,Butts, Craig P.,Armitage, Mark A.,Gallagher, Timothy
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p. 3047 - 3054
(2007/10/03)
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- The development of a new catalytic process: Bu3SnH-catalyzed reductive cyclization of enals and enones
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By sequencing two known reactions, a new catalytic carbon-carbon bond- forming process, the Bu3SnH-catalyzed, PhSiH3-mediated reductive cyclization of enals and enones, has been developed. The addition of EtOH to the reactions leads to reproducibly good yields of the cyclized products; a rationale for including this additive is provided.
- Hays, David S.,Fu, Gregory C.
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p. 8815 - 8832
(2007/10/03)
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- Baker's yeast reduction of arylidenecycloalkanones
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The baker's yeast reduction of arylidene cycloalkanones 5, 6 and 7 occurs initially through the catalysis of different enzymes to give the saturation of the double bond leading to the saturated ketones 9, 15 and 22 and the carbonyl reduction to the (S) allylic alcohols 8a, 14 and 23, possessing 0.99, 0.85 and 0.66 ee, respectively. The latter act as inhibitors for the carbonyl reducing enzyme thus preventing the further reduction of the saturated ketone. These compounds in the absence of allylic alcohols are further reduced to a mixture of diastereomic saturated (S) alcohols of high-moderate enantiomeric purity. Reduction experiments in D2O indicate that saturation of the double bond of 5 occurs by β re face addition of hydrogen, as shown by the obtainment of 10'.
- Fogliato, Giovanni,Fronza, Giovanni,Fuganti, Claudio,Lanati, Simonetta,Rallo, Roberta,Rigoni, Romina,Servi, Stefano
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p. 10231 - 10240
(2007/10/02)
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- LANTHANIDE INDUCED INTRAMOLECULAR COUPLING OF ALDEHYDES AND KETONES WITH ELECTRON-DEFICIENT OLEFINS
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Aldehydes or ketones with a δ,ε-olefin bearing a conjugating electron-withdrawig group undergo reductive cyclization with samarium iodide to afford five membered rings.Diastereoselectivities of >250:1 have been obtained.
- Enholm, Eric J.,Trivellas, Antigone
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p. 1063 - 1066
(2007/10/02)
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