- Late-Stage Intermolecular Allylic C-H Amination
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Allylic amination enables late-stage functionalization of natural products where allylic C-H bonds are abundant and introduction of nitrogen may alter biological profiles. Despite advances, intermolecular allylic amination remains a challenging problem due to reactivity and selectivity issues that often mandate excess substrate, furnish product mixtures, and render important classes of olefins (for example, functionalized cyclic) not viable substrates. Here we report that a sustainable manganese perchlorophthalocyanine catalyst, [MnIII(ClPc)], achieves selective, preparative intermolecular allylic C-H amination of 32 cyclic and linear compounds, including ones housing basic amines and competing sites for allylic, ethereal, and benzylic amination. Mechanistic studies support that the high selectivity of [MnIII(ClPc)] may be attributed to its electrophilic, bulky nature and stepwise amination mechanism. Late-stage amination is demonstrated on five distinct classes of natural products, generally with >20:1 site-, regio-, and diastereoselectivity.
- Clark, Joseph R.,Dixon, Charlie F.,Feng, Kaibo,Han, Wei,Ide, Takafumi,Koch, Vanessa,Teng, Dawei,Wendell, Chloe I.,White, M. Christina
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supporting information
p. 14969 - 14975
(2021/10/01)
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- A Systematic Study of Unsaturation in Lipid Nanoparticles Leads to Improved mRNA Transfection In Vivo
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Lipid nanoparticles (LNPs) represent the leading concept for mRNA delivery. Unsaturated lipids play important roles in nature with potential for mRNA therapeutics, but are difficult to access through chemical synthesis. To systematically study the role of unsaturation, modular reactions were utilized to access a library of 91 amino lipids, enabled by the synthesis of unsaturated thiols. An ionizable lipid series (4A3) emerged from in vitro and in vivo screening, where the 4A3 core with a citronellol-based (Cit) periphery emerged as best. We studied the interaction between LNPs and a model endosomal membrane where 4A3-Cit demonstrated superior lipid fusion over saturated lipids, suggesting its unsaturated tail promotes endosomal escape. Furthermore, 4A3-Cit significantly improved mRNA delivery efficacy in vivo through Selective ORgan Targeting (SORT), resulting in 18-fold increased protein expression over parent LNPs. These findings provide insight into how lipid unsaturation promotes mRNA delivery and demonstrate how lipid mixing can enhance efficacy.
- Lee, Sang M.,Cheng, Qiang,Yu, Xueliang,Liu, Shuai,Johnson, Lindsay T.,Siegwart, Daniel J.
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supporting information
p. 5848 - 5853
(2021/02/05)
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- Regioselective Epoxidations by Cytochrome P450 3A4 Using a Theobromine Chemical Auxiliary to Predictably Produce N-Protected β- or γ-Amino Epoxides
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N-Protected β- and γ-amino epoxides are useful chiral synthons. We report here that the enzyme cytochrome P450 3A4 can catalyze the formation of such compounds in a regio- and stereoselective manner, even in the presence of multiple double bonds or aromatic substituents. To this end, the theobromine chemical auxiliary is used not only to control the selectivity of the enzyme, but also as a masked amine, and to facilitate product recovery. Theobromine predictably directed epoxidation at the double bond of the fourth carbon from the theobromine group. Unlike with most catalysts, the selectivity did not depend on electronic or steric factors but rather on the position of the olefin relative to the theobromine group. (Figure presented.).
- Polic, Vanja,Cheong, Kin Jack,Hammerer, Fabien,Auclair, Karine
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supporting information
p. 3983 - 3989
(2017/11/30)
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- Exhaustive Suzuki-Miyaura reactions of polyhalogenated heteroarenes with alkyl boronic pinacol esters
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A novel Suzuki-Miyaura protocol is described that enables the exhaustive alkylation of polychlorinated pyridines. This method facilitates a formal synthesis of normuscopyridine and the rapid assembly of a dumbbell shaped portion of a [2]rotaxane.
- Laulhé, Sébastien,Blackburn, J. Miles,Roizen, Jennifer L.
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supporting information
p. 7270 - 7273
(2017/07/11)
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- Itraconazole Side Chain Analogues: Structure-Activity Relationship Studies for Inhibition of Endothelial Cell Proliferation, Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) Glycosylation, and Hedgehog Signaling
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Itraconazole is an antifungal drug that was recently found to possess potent antiangiogenic activity and anti-hedgehog (Hh) pathway activity. To search for analogues of itraconazole with greater potency and to understand the structure-activity relationship in both antiangiogenic and Hh targeting activity, 25 itraconazole side chain analogues were synthesized and assayed for inhibition of endothelial cell proliferation and Gli1 transcription in a medulloblastoma (MB) culture. Through this analysis, we have identified analogues with increased potency for inhibiting endothelial cell proliferation and the Hh pathway, as well as VEGFR2 glycosylation that was recently found to be inhibited by itraconazole. An SAR analysis of these activities revealed that potent activity of the analogues against VEGFR2 glycosylation was generally driven by side chains of at least four carbons in composition with branching at the α or β position. SAR trends for targeting the Hh pathway were divergent from those related to HUVEC proliferation or VEGFR2 glycosylation. These results also suggest that modification of the sec-butyl side chain can lead to enhancement of the biological activity of itraconazole.
- Shi, Wei,Nacev, Benjamin A.,Aftab, Blake T.,Head, Sarah,Rudin, Charles M.,Liu, Jun O.
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supporting information; experimental part
p. 7363 - 7374
(2011/12/04)
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- Amphiphilic organocatalyst for schotten-baumann-type tosylation of alcohols under organic solvent free condition
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A Tosylation of primary alcohol with tosyl chloride was performed effectively with an W-hexadecylimidazole catalyst in water containing K 2CO3 aggregation of the catalyst carrying a hydrophobic methylene chain worked as a substitute for organic solvent.
- Asano, Keisuke,Matsubara, Seijiro
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supporting information; experimental part
p. 1757 - 1759
(2009/09/06)
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- A mechanistic alternative for the intramolecular hydroboration of homoallylic amine and phosphine borane complexes
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Intramolecular hydroboration is demonstrated starting from homoallylic amine boranes upon activation by iodine. The process involves a B-iodoborane complex as the intermediate and may occur via internal displacement of iodide by the alkene to generate a cationic borane-alkene π-complex on the way to hydroboration products. The reaction can be carried out using a catalytic amount of iodine. Copyright
- Scheideman, Matthew,Shapland, Peter,Vedejs, Edwin
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p. 10502 - 10503
(2007/10/03)
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- Regiochemical and Stereochemical Studies on Halocyclization Reactions of Unsaturated Sulfides
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The regiochemistry and stereochemistry for the halocyclization reactions of unsaturated benzyl sulfides have been examined as a function of tether length, type of unsaturation (carbon-carbon double bond versus carbon-carbon triple bond), substituents, and halogenating agent.Alkenyl sulfides were found to react with iodine or bromine at room temperature to give five-membered ring cycloadducts exclusively over those having four-membered rings, while for larger systems, six-membered ring products are formed preferentially over their five-membered ring isomers and exclusively over the seven-membered ring adducts.The endo- versus exo-regioselectivity of these alkenyl sulfide ring closure most likely reflects the difference in thermodynamic stabilities of the β-halo sulfide cycloadducts, which are able to equilibrate via a common episulfonium intermediate.The efficiency of cyclization process markedly drops off for these alkenyl sulfides as the tether length increases beyond four intervening carbon centers.Thus, while the halogenations of 3-butenyl sulfides and 4-pentenyl sulfides give high yields of cycloadducts, those of 5-hexenyl sulfides afford only small amounts of cyclized products and large quantities of acyclic dibromides.Conversely, the reactions of acetylenic sulfides with iodine give uniformly high yields and regiochemical control regardless of the tether length.Thus, 3-butynyl and 4-pentynyl sulfides cyclize cleanly to the five-membered ring while 5-hexynyl sulfides give exclusively the six-membered ring.The products arising from these alkynyl sulfide ring closures are believed to be formed under kinetic control.The methodology has been applied to the synthesis of unusual bicyclic β-lactams related to the penicillin family of antibiotics.
- Ren, Xiao-Feng,Turos, Edward,Lake, Charles H.,Churchill, Melvyn Rowen
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p. 6468 - 6483
(2007/10/03)
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- Enantioselective intramolecular cyclopropanation of N-allylic-and N-homoallylic diazoacetamides catalyzed by chiral dirhodium(II) catalysts
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Diazodecomposition of N-(tert-butyl)-N-(3-buten-1-yl)diazoacetamides catalyzed by dirhodium(II) tetrakis[methyl 2-pyrrolidone-5(S)-carboxylate], Rh2(5S-MEPY)4, and tetrakis[methyl 2-oxazolidinone-4(S)-carboxylate], Rh2(4S-
- Doyle, Michael P.,Eismont, Michail Y.,Protopopova, Marina N.,Kwan, Michelle M. Y.
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p. 1665 - 1674
(2007/10/02)
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- Syntheses of the Sex Pheromone of the European Pine Shoot Moth (Rhyacionia buoliana). The Grignard Route
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Grignard-Kopplungen zwischen zwei entsprechenden Synthonen fuehren zum (E)-9-Dodecen-1-ylacetat (1), dem Sexuallockstoff des Kiefernknospentriebwicklers (Rhyacionioa buoliana).Als solche Synthon-Paare wurden 1-Brom-(E)-2-penten (2) und 7-Bromheptyltetrahydropyranylether (3) bzw. (E)-3-Hexen-1-yltosylat (4) und 6-Bromhexyltrimethylsilylether (5) eingesetzt.Das Endprodukt (1) und die wichtigsten Zwischenprodukte wurden durch ihre 1H- und 13C-NMR-Spektren charakterisiert.Durch die zweite Synthese wurden 100percent Regio- und 99percent Stereoselektivitaet erreicht.
- Popovici, N.,Botar, A. A.,Barabas, A.,Oprean, I.,Hodosan, F.
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