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Hönig M, Carreira EM. Total Synthesis and Structural Revision of a Harziane Diterpenoid. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201912982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Hönig M, Carreira EM. Total Synthesis and Structural Revision of a Harziane Diterpenoid. Angew Chem Int Ed Engl 2019; 59:1192-1196. [PMID: 31692208 DOI: 10.1002/anie.201912982] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/03/2019] [Indexed: 01/12/2023]
Abstract
The first total synthesis of nominal harziane diterpenoid 1 is disclosed, whose spectral characteristics did not match those of the reported natural product. Stereochemical analysis and subsequent synthesis of the epimeric tertiary alcohol led to reassignment of configuration of the natural product as shown for 2. At the heart of the synthesis is an enyne cycloisomerization that sets a key quaternary stereocenter within a cyclobutane with high diastereocontrol. The route features strategies for the synthesis of the highly congested 6-5-7-4 carbon skeleton characteristic of the caged harziane diterpenoids.
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Schneider M, Richter MJR, Krautwald S, Carreira EM. Asymmetric Synthesis of the Tricyclooctane Core of Trachylobane Natural Products and Related Terpenoids. Org Lett 2019; 21:8705-8707. [PMID: 31603687 DOI: 10.1021/acs.orglett.9b03303] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enantioselective synthesis of a highly versatile building block en route to trachylobanes and related terpenoids is presented. The synthesis features diastereoselective Diels-Alder cycloaddition reaction, a cyclopropanation/homoquadricyclane rearrangement cascade, and palladium-catalyzed C-H acetoxylation. The targeted tricyclooctane was obtained in 20% yield over 8 steps and in 95% ee. The ketone and alcohol functional groups serve as handles for further elaboration.
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Pfaff P, Samarasinghe KTG, Crews CM, Carreira EM. Reversible Spatiotemporal Control of Induced Protein Degradation by Bistable PhotoPROTACs. ACS CENTRAL SCIENCE 2019; 5:1682-1690. [PMID: 31660436 PMCID: PMC6813558 DOI: 10.1021/acscentsci.9b00713] [Citation(s) in RCA: 157] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Indexed: 05/09/2023]
Abstract
Off-tissue effects are persistent issues of modern inhibition-based therapies. By merging the strategies of photopharmacology and small-molecule degraders, we introduce a novel concept for persistent spatiotemporal control of induced protein degradation that potentially prevents off-tissue toxicity. Building on the successful principle of bifunctional all-small-molecule Proteolysis Targeting Chimeras (PROTACs), we designed photoswitchable PROTACs (photoPROTACs) by including ortho-F4-azobenzene linkers between both warhead ligands. This highly bistable yet photoswitchable structural component leads to reversible control over the topological distance between both ligands. The azo-cis-isomer is observed to be inactive because the distance defined by the linker is prohibitively short to permit complex formation between the protein binding partners. By contrast, the azo-trans-isomer is active since it can engage both protein partners to form the necessary and productive ternary complex. Importantly, due to the bistable nature of the ortho-F4-azobenzene moiety employed, the photostationary state of the photoPROTAC is persistent, with no need for continuous irradiation. This technique offers reversible on/off switching of protein degradation that is compatible with an intracellular environment and, therefore, could be useful in experimental exploration of biological signaling pathways-such as those crucial for oncogenic signal transduction. Additionally, this strategy may be suitable for therapeutic intervention to address a variety of diseases. By enabling reversible activation and deactivation of protein degradation, photoPROTACs offer advantages over conventional photocaging strategies that irreversibly release active agents.
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Rössler SL, Petrone DA, Carreira EM. Iridium-Catalyzed Asymmetric Synthesis of Functionally Rich Molecules Enabled by (Phosphoramidite,Olefin) Ligands. Acc Chem Res 2019; 52:2657-2672. [PMID: 31243973 DOI: 10.1021/acs.accounts.9b00209] [Citation(s) in RCA: 206] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The catalytic, asymmetric synthesis of complex molecules has been a core focus of our research program for some time because developments in the area can have an immediate impact on the identification of novel strategies for the synthesis of value-added molecules. In concert with this central interest, we have emphasized the design of ligand scaffolds as a tactic to discover and develop novel chemistry and overcome well-recognized synthetic challenges. Based on our group's work on chiral pool-derived diolefin ligands, we designed and implemented a class of hybrid (phosphoramidite,olefin) ligands, which combines the properties of both phosphoramidite and olefin motifs to impact, fine-tune, and even override the inherent reactivity of the metal center. Specifically, we have utilized these unique modifying ligands to address several recognized limitations in the field of iridium-catalyzed, asymmetric allylic substitution. The methods we have documented typically employ branched, unprotected allylic alcohols as substrates and obviate the need for rigorous exclusion of air and moisture. Following Takeuchi's seminal report demonstrating the high aptitude of Ir(I)-phosphite catalysts for branch-selective allylic substitution, concerted efforts from numerous research laboratories have led to a broadening of the synthetic utility of this reaction class. The first section of this Account outlines the process leading to our discovery of an unprecedented (phosphoramidite,olefin) ligand and its validation in the first iridium-catalyzed amination of branched, unprotected allylic alcohols. This section continues with our work involving heteroatom-based nucleophiles within inter- and intramolecular etherification, thioetherification and spiroketalization processes. The second section highlights the use of readily available carbon nucleophiles possessing sp, sp2, and sp3 hybridization in a series of enantioselective carbon-carbon bond-forming reactions. We describe how alkylzinc, allylsilane, and several classes of organotrifluoroborate nucleophiles can be coupled enantioselectively to enable construction of several key motifs including 1,5-dienes, 1,4-dienes, and 1,4-enynes. Since the unique electronic and steric properties of this class of ligands renders the (η3-allyl)-Ir(III) intermediate highly electrophilic, even weak nucleophiles such as alkyl olefins can be used. We also show that more nucleophilic alkene motifs such as enamines and in situ generated ketene acetals smoothly participate in substitution reactions with allylic alcohols to yield valuable piperidines and γ,δ-unsaturated esters, respectively. The concept of stereodivergent dual catalysis, which synergistically combines chiral amine catalysis with iridium catalysis to furnish α-allylated aldehydes containing two independently controllable stereocenters is then discussed. This process has enabled the independent, stereoselective synthesis of all four possible product stereoisomers from a single set of starting materials, and was highlighted in the stereodivergent synthesis of Δ9-tetrahydrocannabinol. This Account concludes with an overview of our organometallic mechanistic studies regarding relevant intermediates within the catalytic cycle of this class of allylic substitution. These studies have allowed us to better understand the origin of the unique characteristics exhibited by this catalyst in comparison to related systems.
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Brandstätter M, Huwyler N, Carreira EM. Gold(i)-catalyzed stereoselective cyclization of 1,3-enyne aldehydes by a 1,3-acyloxy migration/Nazarov cyclization/aldol addition cascade. Chem Sci 2019; 10:8219-8223. [PMID: 31857887 PMCID: PMC6839590 DOI: 10.1039/c9sc02828e] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/22/2019] [Indexed: 01/10/2023] Open
Abstract
Stereoselective synthesis of bicyclo[3.3.0]octenones from chiral 1,3-enyne aldehydes bearing propargylic acetates is described. The method is based on a Au(i)-catalyzed domino sequence with concomitant transfer of chirality involving 1,3-acyloxy migration followed by Nazarov cyclization and an unprecedented aldol addition. The method furnishes densely functionalized bicyclic structures in high yields, with up to 97% ee and good diastereoselectivity.
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Sandmeier T, Goetzke FW, Krautwald S, Carreira EM. Iridium-Catalyzed Enantioselective Allylic Substitution with Aqueous Solutions of Nucleophiles. J Am Chem Soc 2019; 141:12212-12218. [DOI: 10.1021/jacs.9b05830] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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83
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Sempere Y, Alfke JL, Rössler SL, Carreira EM. Morpholine Ketene Aminal as Amide Enolate Surrogate in Iridium‐Catalyzed Asymmetric Allylic Alkylation. Angew Chem Int Ed Engl 2019; 58:9537-9541. [DOI: 10.1002/anie.201903090] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Indexed: 01/24/2023]
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84
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Sondermann P, Carreira EM. Stereochemical Revision, Total Synthesis, and Solution State Conformation of the Complex Chlorosulfolipid Mytilipin B. J Am Chem Soc 2019; 141:10510-10519. [PMID: 31244189 DOI: 10.1021/jacs.9b05013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Chlorosulfolipids constitute a structurally intriguing and synthetically challenging class of marine natural products that are isolated from mussels and freshwater algae. The most complex structure from this family of compounds is currently represented by Mytilipin B, isolated in 2002 from culinary mussel Mytilus galloprovincialis, whose initially proposed structure was shown to be incorrect. In this study, we present the synthesis of four diastereomers which allowed the reassignment of eight stereocenters and the stereochemical revision of Mytilipin B, along with the determination of the dominant solution-state conformation.
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Sempere Y, Alfke JL, Rössler SL, Carreira EM. Morpholine Ketene Aminal as Amide Enolate Surrogate in Iridium‐Catalyzed Asymmetric Allylic Alkylation. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903090] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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86
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Schreib BS, Carreira EM. Palladium-Catalyzed Regioselective C–H Iodination of Unactivated Alkenes. J Am Chem Soc 2019; 141:8758-8763. [DOI: 10.1021/jacs.9b03998] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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87
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Carreira EM. Organic Letters Global Enterprise. Org Lett 2019; 21:2967. [DOI: 10.1021/acs.orglett.9b00974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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88
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Carreira EM. Twenty Years of Organic Letters: A Platinum Anniversary Collector’s Edition. Org Lett 2019; 21:1943. [DOI: 10.1021/acs.orglett.9b00656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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89
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Isomura M, Petrone DA, Carreira EM. Coordination-Induced Stereocontrol over Carbocations: Asymmetric Reductive Deoxygenation of Racemic Tertiary Alcohols. J Am Chem Soc 2019; 141:4738-4748. [DOI: 10.1021/jacs.9b00862] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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90
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Brandstätter M, Freis M, Huwyler N, Carreira EM. Total Synthesis of (−)‐Merochlorin A. Angew Chem Int Ed Engl 2019; 58:2490-2494. [DOI: 10.1002/anie.201813090] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Indexed: 01/07/2023]
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91
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Brandstätter M, Freis M, Huwyler N, Carreira EM. Total Synthesis of (−)-Merochlorin A. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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92
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93
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Rössler SL, Jelier BJ, Tripet PF, Shemet A, Jeschke G, Togni A, Carreira EM. Pyridyl Radical Cation for C-H Amination of Arenes. Angew Chem Int Ed Engl 2018; 58:526-531. [PMID: 30398683 DOI: 10.1002/anie.201810261] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Indexed: 11/06/2022]
Abstract
Electron-transfer photocatalysis provides access to the elusive and unprecedented N-pyridyl radical cation from selected N-substituted pyridinium reagents. The resulting C(sp2 )-H functionalization of (hetero)arenes furnishes versatile intermediates for the development of valuable aminated aryl scaffolds. Mechanistic studies that include the first spectroscopic evidence of a spin-trapped N-pyridyl radical adduct implicate SET-triggered, pseudo-mesolytic cleavage of the N-X pyridinium reagents mediated by visible light.
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Rössler SL, Jelier BJ, Tripet PF, Shemet A, Jeschke G, Togni A, Carreira EM. Pyridyl Radical Cation for C−H Amination of Arenes. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201810261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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95
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Boshkow J, Scattolin T, Schoenebeck F, Carreira EM. [1,3]-Sigmatropic Shift of an Allylic Chloride. Helv Chim Acta 2018. [DOI: 10.1002/hlca.201800148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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96
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Richter MJR, Schneider M, Brandstätter M, Krautwald S, Carreira EM. Total Synthesis of (-)-Mitrephorone A. J Am Chem Soc 2018; 140:16704-16710. [PMID: 30412398 DOI: 10.1021/jacs.8b09685] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The first synthesis of (-)-mitrephorone A is disclosed along with discussion and study of synthetic strategies. The natural product includes a highly congested hexacyclic ent-trachylobane diterpenoid framework featuring a rare, embedded oxetane. The synthetic analysis presented dissects a number of approaches for the synthesis of the central oxetane, including carbonyl-olefin photocycloadditions, Prins-type cyclizations, and oxidative ring closures. In the successful route, three [4 + 2] cycloadditions enable rapid construction of all carbocycles. A novel late-stage oxidative cyclization of a hydroxy diosphenol with Koser's reagent furnishes the pivotal oxetane moiety.
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97
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Kravina AG, Carreira EM. Total Synthesis of Epicolactone. Angew Chem Int Ed Engl 2018; 57:13159-13162. [DOI: 10.1002/anie.201807709] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Indexed: 11/05/2022]
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98
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Teiber JF, Xiao J, Kramer GL, Ogawa S, Ebner C, Wolleb H, Carreira EM, Shih DM, Haley RW. Identification of biologically active δ-lactone eicosanoids as paraoxonase substrates. Biochem Biophys Res Commun 2018; 505:87-92. [PMID: 30241945 DOI: 10.1016/j.bbrc.2018.09.083] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 01/08/2023]
Abstract
The mammalian paraoxonases (PONs 1, 2 and 3) are a family of esterases that are highly conserved within and between species. They exhibit antioxidant and anti-inflammatory activities. However, their physiological function(s) and native substrates are uncertain. Previous structure-activity relationship studies demonstrate that PONs have a high specificity for lipophilic lactones, suggesting that such compounds may be representative of native substrates. This report describes the ability of PONs to hydrolyze two bioactive δ-lactones derived from arachidonic acid, 5,6-dihydroxy-eicosatrienoic acid lactone (5,6-DHTL) and cyclo-epoxycyclopentenone (cyclo-EC). Both lactones were very efficiently hydrolyzed by purified PON3. PON1 efficiently hydrolyzed 5,6-DHTL, but with a specific activity about 15-fold lower than PON3. 5,6-DHTL was a poor substrate for PON2. Cyclo-EC was a poor substrate for PON1 and not hydrolyzed by PON2. Studies with the PON inhibitor EDTA and a serine esterase inhibitor indicated that the PONs are the main contributors to hydrolysis of the lactones in human and mouse liver homogenates. Studies with homogenates from PON3 knockout mouse livers indicated that >80% of the 5,6-DHTL and cyclo-EC lactonase activities were attributed to PON3. The findings provide further insight into the structural requirements for PONs substrates and support the hypothesis that PONs, particularly PON1 and PON3, evolved to hydrolyze and regulate a class of lactone lipid mediators derived from polyunsaturated fatty acids.
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100
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Sempere Y, Carreira EM. Trimethyl Orthoacetate and Ethylene Glycol Mono-Vinyl Ether as Enolate Surrogates in Enantioselective Iridium-Catalyzed Allylation. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201803558] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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