journal
https://read.qxmd.com/read/38144170/aryl-annulation-a-powerful-simplifying-retrosynthetic-disconnection
#1
JOURNAL ARTICLE
Rachel M Gillard, Jianjun Zhang, Richard Steel, Jocelyn Wang, Jessica L Strull, Bin Cai, Nilanjana Chakraborty, Dale L Boger
Retrosynthetic deconstruction of a core aromatic ring is an especially simplifying retrosynthetic step, reducing the complexity of the precursor synthetic target. Moreover, when implemented to provide a penultimate intermediate, it enables late-stage divergent aryl introductions, permitting deep-seated core aryl modifications ordinarily accessible only by independent synthesis. Herein, we highlight the use of a ketone carbonyl group as the functionality to direct such late-stage divergent aryl introductions onto a penultimate intermediate with a projected application in the total synthesis of vinblastine and its presently inaccessible analogs containing indole replacements...
January 2024: Synthesis
https://read.qxmd.com/read/37915377/palladium-catalyzed-dearomatization-of-benzothiophenes-isolation-and-functionalization-of-a-discrete-dearomatized-intermediate
#2
JOURNAL ARTICLE
Andrew John Intelli, Mohan Pal, Manikandan Selvaraju, Ryan A Altman
A Pd-catalyzed decarboxylative dearomatization reaction of a heterocyclic substrate enables access to an uncommon reaction intermediate that rearomatizes in the presence of amine bases in a net C-H functionalization sequence. The dearomatized benzo[ b ]thiophene intermediate bears an exocyclic alkene that can be functionalized through cycloaddition and halogenation reactions to deliver complex heterocyclic products.
November 2023: Synthesis
https://read.qxmd.com/read/37790600/reactions-of-benzylboronate-nucleophiles
#3
JOURNAL ARTICLE
Timothy J Barker, Andrew Bogatkevich, Dallas W Crowder, Sophia G Gierszal, Jacob C Hayes, Michael R Hollerbach, Richard W Russell
This short review summarizes our laboratory's development of benzylboronic esters as nucleophiles. Activation of the benzylboronic ester is achieved by irreversible coordination of an alkyllithium Lewis base to form a nucleophilic benzylboronate. This boronate was found to react with aldehydes, imines, ketones and alkyl bromides. A copper catalyst was employed in reactions of the boronate with epoxides and aziridines.
September 2023: Synthesis
https://read.qxmd.com/read/38314182/synthesis-of-polycyclic-imidazoles-via-%C3%AE-c-h-n-h-annulation-of-alicyclic-amines
#4
JOURNAL ARTICLE
Subhradeep Dutta, Kamal Bhatt, Fabian Cuffel, Daniel Seidel
Secondary alicyclic amines are converted to their corresponding ring-fused imidazoles in a simple procedure consisting of oxidative imine formation followed by a van Leusen reaction. Amines with an existing α-substituent undergo regioselective ring-fusion at the α'-position. This method was utilized in a synthesis of fadrozole.
August 2023: Synthesis
https://read.qxmd.com/read/38249784/uncatalyzed-carbometallation-involving-group-13-elements-carboboration-and-carboalumination-of-alkenes-and-alkynes
#5
JOURNAL ARTICLE
Yudong Liu, K A Woerpel
Carbometallation of alkenes and alkynes are powerful carbon-carbon bond-forming reactions. The use of compounds containing bonds between carbon and group 13 elements, particularly boron and aluminum, are particularly attractive because of the versatility of subsequent transformations. Uncatalyzed carboboration and carboalumination represent less common classes of reactions. This Short Review discusses uncatalyzed carboboration and carboalumination reactions of alkenes and alkynes, including the reaction design and mechanism...
August 2023: Synthesis
https://read.qxmd.com/read/37691879/synthesis-of-guaipyridine-alkaloids-rupestine-m-and-l-by-cycloaddition-cycloreversion-of-an-intermediate-1-4-oxazinone
#6
JOURNAL ARTICLE
Jonathan R Scheerer, Ella B Leeth, Jennifer A Sprow
A new method to prepare 1,4-oxazinone intermediates was developed based on aza-conjugate addition of β-amino alcohols to electron-deficient alkyne precursors. A tandem intramolecular cycloaddition/cycloreversion reaction sequence was evaluated, leading to the synthesis of the guaipyridine alkaloid natural products rupestine M and L. Starting from (-)-citronellal and thus a known configuration of the C5 stereocenter, a revised absolute configuration of natural rupestine L is suggested based on optical rotation...
August 2023: Synthesis
https://read.qxmd.com/read/37600240/simplified-synthesis-of-an-air-stable-copper-complexed-josiphos-ligand-via-ugi-s-amine-complete-preparation-and-analysis-from-ferrocene
#7
JOURNAL ARTICLE
Emma C Murphy, Jeffrey S Johnson
Ligands containing ferrocene backbones often feature both planar chirality and asymmetric centers, making them attractive options for asymmetric catalysis. Ugi's amine is a ubiquitous ferrocene-based chiral building block that can be functionalized to form a variety of tunable Josiphos ligands; however, few sources lay out the route from start to finish. Starting from ferrocene, we compile a synthetic route to an air- and moisture-stable copper(I)-Josiphos complex via enantiopure Ugi's amine, providing a potential one-stop shop for the synthesis of a wide range of Josiphos ligands...
August 2023: Synthesis
https://read.qxmd.com/read/37457378/synthesis-of-n-acylsulfenamides-from-amides-and-n-thiosuccinimides
#8
JOURNAL ARTICLE
Jessica T Liu, Daniel S Brandes, Nathaniel S Greenwood, Jonathan A Ellman
Herein is reported a robust and general method for the preparation of N -acylsulfenamides, important functionalities that have recently been utilized as central inputs for the asymmetric synthesis of high oxidation state sulfur compounds. This straightforward transformation proceeds by reaction of primary amides, carbamates, sulfonamides, sulfinamides, and ureas with stable N -thiosuccinimides or N -thiophthalimides, which in turn are prepared in a single step from commercial thiols. The use of stable N -thiosuccinimide and N -thiophthalimide reactants is desirable because it obviates the use of highly reactive sulfenyl chlorides...
August 2023: Synthesis
https://read.qxmd.com/read/37457884/catalytic-dienylation-an-emergent-strategy-for-the-stereoselective-construction-of-conjugated-dienes-and-polyenes
#9
JOURNAL ARTICLE
Jasimuddin Ahmed, Graham C Haug, Viet D Nguyen, Arka Porey, Ramon Trevino, Oleg V Larionov
Stereoselective construction of conjugated dienes and polyenes has remained an enduring synthetic problem, due to the central roles they play in natural product synthesis, methodology, and medicine. This review focuses on the recent developments in dienylation as an emerging strategy for the direct installation of unsaturated four carbon atom units of conjugated π-systems, outlining the regio- and stereoselectivity, as well as the synthetic scope of reactions with various dienylating reagents and the mechanistic implications of the catalytic cross-coupling processes that are used to enable dienylation...
June 2023: Synthesis
https://read.qxmd.com/read/37841289/carbonyl-allylation-and-crotylation-historical-perspective-relevance-to-polyketide-synthesis-and-evolution-of-enantioselective-ruthenium-catalyzed-hydrogen-auto-transfer-processes
#10
JOURNAL ARTICLE
Eliezer Ortiz, Connor Saludares, Jessica Wu, Yoon Cho, Catherine G Santana, Michael J Krische
The evolution of methods for carbonyl allylation and crotylation of alcohol proelectrophiles culminating in the design of iodide-bound ruthenium-JOSIPHOS catalysts is prefaced by a brief historical perspective on asymmetric carbonyl allylation and its relevance to polyketide construction. Using gaseous allene or butadiene as precursors to allyl- or crotylruthenium nucleophiles, respectively, new capabilities for carbonyl allylation and crotylation have been unlocked, including stereo- and site-selective methods for the allylation and crotylation of 1,3-diols and related polyols...
May 2023: Synthesis
https://read.qxmd.com/read/37151600/indication-of-pd-c-or-cu-c-intermediate-in-respective-bimetallic-nanoclusters-pd-au-pvp-or-cu-au-pvp-catalyzed-oxidations-of-endo-4-oxatricyclo-5-2-1-0-2-6-8-decene-and-tetrahydro-%C3%AE-carbolines
#11
JOURNAL ARTICLE
Shunya Morita, Zhaoyang Ren, Lingaraju Gorla, Zongbo Tong, Edruce Edouarzin, Boris Averkiev, Victor W Day, Duy H Hua
Catalytic oxidations of tricyclic endo -norbornene-fused tetrahydrofuran with bimetallic nanoclusters Cu/Au-PVP and H2 O2 or t -BuOOH as an oxidant provided C-H bond oxidation adjacent to the ether function and 4-oxa-tricyclo[5.2.1.0]-8,9- exo -epoxydecane ( 4 ), however, oxidation with Pd/Au-PVP took place at the C=C function giving epoxide 4 and oxidative three-bond forming dimeric product, dodecahydro-1,4:6,9-dimethanodibenzofurano[2,3-b:7,8-b']bisoxolane ( 5 ). Formation of the latter suggests the involvement of a reactive Pd-C intermediate...
April 2023: Synthesis
https://read.qxmd.com/read/37274078/synthesis-of-1-1-disubstituted-allenylic-silyl-ethers-through-iron-catalyzed-regioselective-c-sp-2-%C3%A2-h-functionalization-of-allenes
#12
JOURNAL ARTICLE
Ruiqi Ding, Yidong Wang, Yi-Ming Wang
We report a synthesis of allenylic silyl ethers through iron-catalyzed functionalization of the C(sp2 )─H bonds of monosubstituted alkylallenes. In the presence of a cyclopentadienyliron dicarbonyl based catalyst and triisopropylsilyl triflate as a silylation agent, a variety of aryl aldehydes were suitable coupling partners in this transformation, furnishing a collection of 1,1-disubstituted allenylic triisopropylsilyl ethers as products in moderate to excellent yields as a single regioisomer. Lithium bistriflimide was identified as a critical additive in this transformation...
March 2023: Synthesis
https://read.qxmd.com/read/36644007/building-chemical-probes-based-on-the-natural-products-ym-254890-and-fr900359-advances-toward-scalability
#13
JOURNAL ARTICLE
Matthew R Medcalf, Ruby L Krueger, Zach T Medcalf, Peter A Rosston, Yu Zhu, Kevin M Kaltenbronn, Kendall J Blumer, Kevin D Moeller
The biological activity of natural products YM-254890 (YM) and FR900359 (FR) has led to significant interest in both their synthesis and the construction of more simplified analogs. While the simplified analogs lose much of the potency of the natural products, they are of interest in their own right, and their synthesis has revealed synthetic barriers to the family of molecules that need to be addressed if a scalable synthesis of YM and FR analogs is to be constructed. In the work described here, a synthetic route to simplified analogs of YM is examined and strategies for circumventing some of the challenges inherent to constructing the molecules are forwarded...
January 2023: Synthesis
https://read.qxmd.com/read/36744023/enantioselective-dearomative-alkynylation-of-chromanones-opportunities-and-obstacles
#14
JOURNAL ARTICLE
Yong Guan, Tadas Buivydas, Remy F Lalisse, Rameez Ali, Christopher Hadad, Anita E Mattson
A catalytic and highly enantioselective dearomative alkynylation of chromanones has been discovered that enables the construction of biologically relevant tertiary ether stereogenic centers. This methodology is robust, accommodating a variety of alkynes and chromanones. More than 40 substrates tested gave rise to >90% ee. Computational studies have indicated that the optimal indanyl ligand identified for most cases likely affords a network of supportive, non-covalent interactions that drive the enantioselective nature of the reaction...
October 2022: Synthesis
https://read.qxmd.com/read/36330045/selective-csp-3-f-bond-functionalization-with-lithium-iodide
#15
JOURNAL ARTICLE
Kaluvu Balaraman, Samantha Kyriazakos, Rachel Palmer, F Yushra Thanzeel, Christian Wolf
A highly efficient method for C-F bond functionalization of a broad variety of activated and unactivated aliphatic substrates with inexpensive lithium iodide is presented. Primary, secondary, tertiary, benzylic, propargylic and α-functionalized alkyl fluorides react in chlorinated or aromatic solvents at room temperature or upon heating to the corresponding iodides which are isolated in 91-99% yield. The reaction is selective for aliphatic monofluorides and can be coupled with in situ nucleophilic iodide replacements to install carbon-carbon, carbon-nitrogen and carbon-sulfur bonds with high yields...
October 2022: Synthesis
https://read.qxmd.com/read/36187077/enantioselective-syntheses-of-yohimbine-alkaloids-proving-grounds-for-new-catalytic-transformations
#16
JOURNAL ARTICLE
Eric R Miller, Karl A Scheidt
The total synthesis of bioactive alkaloids is an enduring challenge and an indication of the state of the art of chemical synthesis. With the explosion of catalytic asymmetric methods over the past three decades, these compelling targets have been fertile proving grounds for enantioselective bond forming transformations. These activities are summarized herein both to highlight the power and versatility of these methods and to instill future inspiration for new syntheses of these privileged natural products.
2022: Synthesis
https://read.qxmd.com/read/36147611/synthesis-of-structurally-defined-nitroxide-spin-labeled-glycolipids-as-useful-probes-for-electron-paramagnetic-resonance-epr-spectroscopy-studies-of-cell-surface-glycans
#17
JOURNAL ARTICLE
Xin Yan, Zhongwu Guo
Four glycolipids carrying different glycans and a nitroxide free radical spin at the glycan non-reducing end were designed and synthesized from free glucose and maltooligosaccharides by an efficient and streamlined synthetic strategy. The main features of this synthetic strategy include regioselective functionalization of the free carbohydrates and coupling of the radical spin label with functionalized free glycans as the last synthetic step. These glycolipids are useful probes for the study of cell surface glycans by electron paramagnetic resonance spectroscopy...
2022: Synthesis
https://read.qxmd.com/read/35422533/condensation-based-methods-for-the-c-h-bond-functionalization-of-amines
#18
JOURNAL ARTICLE
Weijie Chen, Daniel Seidel
This review aims to provide a comprehensive overview of condensation-based methods for the C-H bond functionalization of amines that feature azomethine ylides as key intermediates. These transformations are typically redox-neutral and share common attributes with classic name reactions such as the Strecker, Mannich, Friedel-Crafts, Pictet-Spengler, and Kabachnik-Fields reaction, while incorporating a redox-isomerization step. This approach provides an ideal platform to rapidly transform simple starting materials into complex amines...
November 2021: Synthesis
https://read.qxmd.com/read/34707322/fluorine-retentive-strategies-for-the-functionalization-of-gem-difluoroalkenes
#19
JOURNAL ARTICLE
Jacob P Sorrentino, Ryan A Altman
gem -Difluoroalkenes are readily available fluorinated building blocks, and the fluorine-induced electronic perturbations of the alkenes enables a wide array of selective functionalization reactions. However, many reactions of gem -difluoroalkenes result in a net C─F functionalization to generate monofluorovinyl products or addition of F to generate trifluoromethyl-containing products. In contrast, fluorine-retentive strategies for the functionalization of gem -difluoroalkenes remain less generally developed, and is now becoming a rapidly developing area...
November 2021: Synthesis
https://read.qxmd.com/read/35431351/a-convenient-protecting-group-for-uridine-ureido-nitrogen-4-4-bisfluorophenyl-methoxymethyl-group
#20
JOURNAL ARTICLE
Katsuhiko Mitachi, David Mingle, Michio Kurosu
(4,4'-Bisfluorophenyl)methoxymethyl (BFPM) group of uridine ureido nitrogen shows good relative stability in a variety of chemical transformation reactions for uridine. The BFPM group can be cleaved via 2% of TFA in CH2 Cl2 without affecting the Boc group.
August 2021: Synthesis
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