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1.
Nat Prod Rep ; 41(5): 813-833, 2024 May 22.
Article in English | MEDLINE | ID: mdl-38294038

ABSTRACT

Covering: 1998 up to the end of 2023Since its initial disclosure in 1951, the Kornblum DeLaMare rearrangement has proved an important synthetic transformation and has been widely adopted as a biomimetic step in natural product synthesis. Utilising the base catalysed decomposition of alkyl peroxides to yield a ketone and alcohol has found use in many syntheses as well as a key strategic step, including the unmasking of furans, as a biomimetic synthetic tool, and the use of the rearrangement to install oxygen enantioselectively. Since ca. 1998, its impact as a synthetic transformation has grown significantly, especially given the frequency of use in natural product syntheses, therefore this 25 year time period will be the focus of the review.


Subject(s)
Biological Products , Chemistry Techniques, Synthetic , Biological Products/chemical synthesis , Biological Products/chemistry , Catalysis , Furans/chemical synthesis , Furans/chemistry , Ketones/chemistry , Ketones/chemical synthesis , Molecular Structure , Stereoisomerism , Chemistry Techniques, Synthetic/history , Chemistry Techniques, Synthetic/methods , History, 20th Century , History, 21st Century
2.
J Org Chem ; 89(1): 484-497, 2024 Jan 05.
Article in English | MEDLINE | ID: mdl-38143311

ABSTRACT

The direct transformation of 1,3-dienes into valuable 2,5-diarylfurans using transition-metal-free conditions is presented. By employing a simple oxidation─dehydration sequence on readily accessible 1,3-dienes, important 2,5-diarylfuran building blocks frequently used in medicinal and material chemistry are prepared. The oxidation step is realized using singlet oxygen, and the intermediate endoperoxide is dehydrated under metal-free conditions and at ambient temperature using the Appel reagent. Notably, this sequence can be streamlined into continuous flow, thereby eliminating the isolation of the intermediate, often unstable endoperoxide. This leads to a significant improvement in isolated yields (ca. 27% average increase) of the 2,5-diarylfurans while also increasing safety and reducing waste. Our transition-metal-free synthetic approach to 2,5-diarylfurans delivers several important furan building blocks used commonly in medicinal chemistry and as optoelectronic materials, including short-chain linearly conjugated furan oligomers. Consequently, we also complete a short study of the optical and electrochemical properties of a selection of these novel materials.

3.
J Org Chem ; 88(6): 3965-3969, 2023 Mar 17.
Article in English | MEDLINE | ID: mdl-36854174

ABSTRACT

The synthesis of a new family of naphthalenoid C2-symmetric clefts has been realized through a four-step synthetic sequence giving three C2-symmetric clefts and a rare nonsymmetric example. Subsequently, stereoselective reduction of the carbonyl groups at C-8 and C-16 then provides cleft molecules with hydrogen bonding potential. Using single-crystal X-ray and computational analysis, the cleft angle of the dione has been determined.

4.
Beilstein J Org Chem ; 16: 1983-1990, 2020.
Article in English | MEDLINE | ID: mdl-32831955

ABSTRACT

An intermolecular radical addition, using photoredox catalysis, to allenamides and allencarbamates is reported. This transformation synthesizes N-acyl-N'-aryl-N,N'-allylaminals, and proceeds by a conjugated N-acyliminium intermediate that previously has principally been generated by electrophilic activation methods. The radical adds to the central carbon of the allene giving a conjugated N-acyliminium that undergoes nucleophilic addition by arylamines and alcohols.

5.
ACS Omega ; 4(1): 785-792, 2019 Jan 31.
Article in English | MEDLINE | ID: mdl-31459359

ABSTRACT

An indium-mediated isomerization of 1,4-dienols to 1,3-dienols is described. This procedure consists of the addition of pentadienylindium, in a protic solvent, to aldehydes giving the kinetic γ-allylation product in high yields. The subsequent conversion of this γ-allylation product to its thermodynamic 1,3-dienol α-isomer can be achieved by its exposure to indium triflate in the presence of a substoichiometric amount of aldehyde at room temperature. This transformation exhibited moderate to good substrate scope and has been shown to proceed by a 2-oxonia Cope rearrangement.

6.
Org Lett ; 21(12): 4892-4895, 2019 06 21.
Article in English | MEDLINE | ID: mdl-31188007

ABSTRACT

The first total synthesis of the tetrasubstituted furan fatty acid (FFA) metabolite 5-[(1 E)-2-carboxyethenyl]-3,4-dimethyl-2-furanpentanoic acid (CeDFP) is reported. CeDFP is a FFA metabolite isolated from shark livers and is related to the known FFA metabolites CMPF and CMPentylF. Key elements of the synthetic route to CeDFP include an iodine-promoted 5- endo- dig cyclization of a 1,2-alkyne diol, a methyllithium-mediated insertion of the C3-methyl group, and a Au(I)-catalyzed intermolecular hydroarylation to introduce the unsaturated ester.

7.
J Cell Biochem ; 119(7): 6094-6103, 2018 07.
Article in English | MEDLINE | ID: mdl-29574938

ABSTRACT

Resolution of inflammation is now known to be an active process which in part is instigated and controlled by specialized pro-resolving lipid mediators (SPM's) derived from dietary omega-3 fatty acids. Resolvin E1 (Rv E1 ) is one of these SPM's derived from the omega-3 fatty acid eicosapentaenoic acid. Using both molecular and phenotypic functional measures we report that in a model of Lipopolysaccharide (LPS) induced inflammation, Rv E1 attenuated mRNA levels of both interlukin-6 and monocyte chemoattractant protein-1 whilst having no effect on tumor necrosis factor-α or interlukin-1ß in C2C12 skeletal muscle myotubes. Findings at the molecular level were transferred into similar changes in extracellular protein levels of the corresponding genes with the greatest attenuation being noted in IL-6 protein concentrations. Rv E1 instigated beneficial morphological changes through the prevention of LPS induced skeletal muscle atrophy, in tandem with attenuation of the LPS induced reduction in contractile force in tissue engineered skeletal muscle. These findings demonstrate, in our model of endotoxin induced inflammation in skeletal muscle, that Rv E1 has pro-resolving properties in this cell type. Our data provides rationale for further investigation into the mechanistic action of Rv E1 in skeletal muscle, with the vision of having potential benefits for the prevention/resolution of in-vivo skeletal muscle atrophy.


Subject(s)
Eicosapentaenoic Acid/analogs & derivatives , Inflammation/prevention & control , Lipopolysaccharides/toxicity , Muscle Fibers, Skeletal/drug effects , Muscle, Skeletal/drug effects , Muscular Atrophy/prevention & control , Animals , Cells, Cultured , Eicosapentaenoic Acid/pharmacology , Inflammation/chemically induced , Inflammation/metabolism , Inflammation Mediators/metabolism , Mice , Muscle Fibers, Skeletal/pathology , Muscle, Skeletal/pathology , Muscular Atrophy/chemically induced , Muscular Atrophy/metabolism
8.
Org Lett ; 20(4): 1003-1006, 2018 02 16.
Article in English | MEDLINE | ID: mdl-29373031

ABSTRACT

A photoredox catalytic approach to synthetically valuable N-acyl-N'-aryl-N,N'-aminals is described. This method uses the addition of a radical precursor to enamides, with subsequent interception of the cationic iminium intermediate with an arylamine. The reaction has been shown to be compatible with electron-rich and electron-deficient arylamines, and moderate to good levels of diastereoselectivity can be attained using a chiral enamide. Furthermore, the N-acyl-N'-aryl-N,N'-aminal reaction products can be readily cyclized, providing a novel synthetic route to valuable γ-lactams.


Subject(s)
Lactams/chemistry , Catalysis , Cations , Molecular Structure
9.
Chem Commun (Camb) ; 53(47): 6327-6330, 2017 Jun 08.
Article in English | MEDLINE | ID: mdl-28548154

ABSTRACT

Appel reaction conditions have been harnessed to affect a mild biosynthetically inspired dehydration of endoperoxides to deliver multi-substituted electron rich furans. Unlike traditional dehydrative procedures, this method is metal and acid free, and can be achieved under redox neutral conditions. It is general for a range of aryl and alkyl substituted endoperoxides, and is functional group tolerant. Furthermore, this procedure has been used to deliver an effective total synthesis of the furan fatty acid (FFA) F5.

10.
Org Lett ; 18(14): 3502-5, 2016 07 15.
Article in English | MEDLINE | ID: mdl-27355240

ABSTRACT

We report a facile method for the synthesis of 1,3-dienes by a sequential process consisting of a palladium-catalyzed, base-free, Suzuki-Miyaura coupling/isomerization sequence. This sequence couples boronic acids with propargyl alcohols, generating the requisite allene in situ, followed by conversion of the unactivated allene to its 1,3-diene via a hydro-palladation/dehydro-palladation process. This process is general for a range of boronic acids, including boronic acids with electron-donating and -withdrawing groups, as well as heteroarylboronic acids. Key to this process is the boric acid byproduct of the base-free Suzuki-Miyauru coupling, which generates the required palladium-hydrido complex [H-Pd(II)-OB(OH)2] required for the isomerization.

11.
Org Lett ; 16(17): 4606-9, 2014 Sep 05.
Article in English | MEDLINE | ID: mdl-25119671

ABSTRACT

Au(I) activation of allenamides in the presence of phenols leads to the formation of chromanes in moderate to good yields. This catalytic process is dependent on the counterion which facilitates the activation of the in situ formed imine. Furthermore, this iminium can be intercepted by trimethylallyl silane, via the Hosomi-Sakurai reaction, giving a formal procedure for the regioselective intermolecular addition of two carbon nucleophiles to an allenamide at the α- and γ-positions.

12.
J Org Chem ; 78(7): 3476-81, 2013 Apr 05.
Article in English | MEDLINE | ID: mdl-23464745

ABSTRACT

The intermolecular addition of 1,3-dicarbonyl equivalents to endoperoxides in the presence of an organocatalyst yields trans-fused butyrolactones in high yield and enantioselectivities. This methodology expands the synthetic utility of endoperoxides and further underlines their potential as sources of oxygen functionality for natural and non-natural product target synthesis.


Subject(s)
4-Butyrolactone/chemical synthesis , Peroxides/chemistry , 4-Butyrolactone/analogs & derivatives , 4-Butyrolactone/chemistry , Molecular Conformation , Stereoisomerism
13.
Org Biomol Chem ; 10(43): 8669-76, 2012 Nov 21.
Article in English | MEDLINE | ID: mdl-23032707

ABSTRACT

The addition of allyl magnesium and allyl indium reagents to a key TBS protected norbornenyl building block, synthesised in 6-steps from commercially available 1,1-dimethoxy-2,3,4,5-tetrachlorocyclopentadiene, has been achieved providing the syn addition products with high diastereoselectivity. The subsequent exposure of the addition products to metathesis conditions, in the presence of ethene, then provided cis fused[3.0.3]-carbocycles with very high regioselectivity, via a Ring Rearrangement Metathesis (RRM) transformation.


Subject(s)
Alcohols/chemical synthesis , Allyl Compounds/chemistry , Indium/chemistry , Magnesium/chemistry , Norbornanes/chemistry , Alcohols/chemistry , Cyclization , Molecular Structure , Stereoisomerism
14.
Curr Opin Drug Discov Devel ; 13(6): 645-57, 2010.
Article in English | MEDLINE | ID: mdl-21061228

ABSTRACT

Allenamides are electron-deficient equivalents of allenamines, which can participate in a range of cycloaddition reactions giving rise to novel heterocycles and diverse molecular architectures similar to those contained in natural products. This review summarizes some of the research conducted in this field, with particular reference to predicting the stereochemical outcomes of such transformations. The applications of allenamides in cycloaddition transformations are highlighted, providing insight into the potential utility of this under-used synthon.


Subject(s)
Alkadienes/chemistry , Amides/chemistry , Drug Design , Cyclization , Heterocyclic Compounds/chemical synthesis , Molecular Structure , Stereoisomerism
15.
J Org Chem ; 75(15): 5406-9, 2010 Aug 06.
Article in English | MEDLINE | ID: mdl-20670040

ABSTRACT

An intermolecular hydroamination of allenamides with arylamines has been achieved under mild Au(I) catalysis conditions delivering allylamino E-enamides stereoselectively and in high yield. The reaction is made possible via a convenient method for conjugated N-acyliminium formation.

16.
Org Lett ; 12(5): 1128-31, 2010 Mar 05.
Article in English | MEDLINE | ID: mdl-20143846

ABSTRACT

A mild and facile synthesis of enamides has been developed, based on nucleophilic addition of electron-rich aromatic and heteroaromatics to an allenamide unit catalyzed by a gold salt. Yields for the transformation were 29-98%.

17.
Chem Commun (Camb) ; (5): 591-3, 2008 Feb 07.
Article in English | MEDLINE | ID: mdl-18209799

ABSTRACT

A 20-membered macrocyclic thiodepsipeptide has been synthesized as a model for the southern hemisphere of nosiheptide, the key steps being assembly of an acyclic precursor by amide coupling of indole and thiazole fragments followed by formation of the thiolactone in the macrocyclization step.


Subject(s)
Depsipeptides/chemical synthesis , Macrocyclic Compounds/chemical synthesis , Models, Chemical , Sulfhydryl Compounds/chemical synthesis , Cyclization , Depsipeptides/chemistry , Macrocyclic Compounds/chemistry , Magnetic Resonance Spectroscopy/methods , Molecular Conformation , Stereoisomerism , Sulfhydryl Compounds/chemistry , Thiazoles/chemical synthesis , Thiazoles/chemistry
19.
Chem Commun (Camb) ; (21): 2470-1, 2004 Nov 07.
Article in English | MEDLINE | ID: mdl-15514820

ABSTRACT

Highly functionalised six- and seven-membered cyclic ethers bearing a variety of side chains have been synthesised using ring-closing enyne metathesis and subsequent cross metathesis of the intermediate diene; one-pot enyne and cross metathesis has also been accomplished, allowing ring construction and side chain introduction to be performed in a single operation.


Subject(s)
Alkynes/chemistry , Ethers/chemical synthesis , Catalysis , Cyclization , Molecular Conformation , Oxidation-Reduction
20.
J Org Chem ; 68(11): 4239-46, 2003 May 30.
Article in English | MEDLINE | ID: mdl-12762722

ABSTRACT

An approach to highly functionalized tetrahydrofuran derivatives based upon a novel Oxa-Michael/Michael dimerization of cis-gamma-hydroxyenones is presented. The reaction begins with either 1,2-dioxines or trans-gamma-hydroxyenones and proceeds by addition of one molecule of trans-gamma-hydroxyenone to another molecule of cis- or trans-gamma-hydroxyenone catalyzed by an alkoxide or hydroxide base. Subsequent intramolecular Michael addition of the keto-enolate gives the observed tetrahydrofurans. Substitution at both the 2- and 4-positions of the gamma-hydroxyenone is tolerated; however, for 4-substituted gamma-hydroxyenones, selectivity issues arise due to the possibility of heterochiral or homochiral dimerizations. The major products were those with all contiguous groups trans.

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