- Stereocontrolled Construction of the A-Ring of Nitiol Using a Pauson-Khand Cycloaddition-Ring Fragmentation Strategy
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(matrix presented) A stereocontrolled construction of the A-ring of nitiol (1) is presented. Key features in this approach are a diastereoselective Pauson-Khand cycloaddition and a Norrish type 1 fragmentation reaction.
- Wilson, Michael S.,Dake, Gregory R.
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- Dearomatizing radical cyclizations and cyclization cascades triggered by electron-transfer reduction of amide-type carbonyls
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Highly selective dearomatizing radical cyclizations and cyclization cascades, triggered by single electron transfer to amide-type carbonyls by SmI2-H2O-LiBr, provide efficient access to unprecedented spirocyclic scaffolds containing
- Huang, Huan-Ming,Procter, David J.
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- PYRIMIDINE AND PYRIDINE DERIVATIVES AND USE IN TREATMENT, AMELIORATION OR PREVENTION OF INFLUENZA THEREOF
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Provided herein is a compound of formula (I), optionally in the form of a pharmaceutically acceptable salt, solvate, polymorph, prodrug, codrug, cocrystal, tautomer, racemate, enantiomer, or diastereomer or mixture thereof, which is useful in treating, ameliorating or preventing influenza.
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Page/Page column 151; 152
(2017/12/28)
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- Radical-Radical Cyclization Cascades of Barbiturates Triggered by Electron-Transfer Reduction of Amide-Type Carbonyls
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Radical-radical cyclization cascades, triggered by single-electron transfer to amide-type carbonyls by SmI2-H2O, convert simple achiral barbiturates in one step to hemiaminal- or enamine-containing tricyclic scaffolds containing up to five contiguous stereocenters (including quaternary stereocenters). Furthermore, we describe the surprising beneficial effect of LiBr on the most challenging of the radical-radical cyclization cascades. An alternative fragmentation-radical cyclization sequence of related substrates allows access to bicyclic uracil derivatives. The radical-radical cyclization process constitutes the first example of a radical cascade involving ET reduction of the amide carbonyl. Products of the cascade can be readily manipulated to give highly unusual and medicinally relevant bi- and tricyclic barbiturates.
- Huang, Huan-Ming,Procter, David J.
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supporting information
p. 7770 - 7775
(2016/07/06)
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- Reactions of Methyl-Substituted Hex-5-enyl and Pent-4-enyl Radicals
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Relative and absolute kinetic data have been determined for ring closure of methyl-substituted hex-5-enyl radicals: 2-methyl-(10a), 3-methyl-(4a), 4-methyl-(5a), 2,2-dimethyl-(10c), 3,3-dimethyl-(4c) and 4,4-dimethyl-hex-5-enyl (5c) radicals, generated by interaction of tributylstannane with the corresponding bromides (1a)-(3a) and (1c)-(3c).Each radical undergoes regiospecific or highly regioselective 1,5-cyclization more rapidly than does the unsubstituted radical (4d).The rate enhancements, which arise mainly from lowering of the activation energy, can be rationalized in terms of the gem-dimethyl effect. 1,5-Ring closures of monosubstituted species are stereoselective: 2-methyl- and 4-methyl-hex-5-enyl radicals (10a) and (5a) give mainly trans products, whereas 3-methylhex-4-enyl radical gives mainly the cis.This behaviour reflects the effect of the substituent on the stabilities of cyclic transition complexes in chair-like conformations.Ring closure of 2,2-dimethylpent-4-enyl radical or of 3,3-dimethylpent-4-enyl radical (19) could not be detected.
- Beckwith, Athelstan L. J.,Easton, Christopher J.,Lawrence, Tony,Serelis, Algirdas K.
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p. 545 - 556
(2007/10/02)
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- INTRAMOLECULAR CYCLOADDITION OF CARBONYL YLIDES GENERATED FROM α-DIAZO KETONES
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Two cases of intramolecular cycloaddition of carbonyl ylides, formed from the α-diazo-ketones 1 and 8, to a C=C double bond within the molecule are described.The structures of the products 4a and 10 have been established from chemical and spectroscopic ev
- Gillon, A.,Ovadia, D.,Kapon,M.,Bien, S.
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p. 1477 - 1484
(2007/10/02)
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