Read by QxMD icon Read

Journal of Organic Chemistry

Hyunjung Oh, Sangil Han, Ashok Kumar Pandey, Sang Hoon Han, Neeraj Kumar Mishra, Saegun Kim, Rina Chun, Hyung Sik Kim, Jihye Park, In Su Kim
The rhodium(III)-catalyzed C-H functionalization followed by intramolecular annulation reactions between azobenzenes and sulfoxonium ylides are described. This protocol leads to the efficient formation of 3-acyl (2H)-indazoles with a range of substrate scope. A high level of chemoselectivity and functional group tolerance of this transformation were also observed.
March 16, 2018: Journal of Organic Chemistry
Christopher Ryan Shugrue, Aaron L Featherston, Rachel M Lackner, Angela Lin, Scott J Miller
Phosphothreonine (pThr)-embedded peptide catalysts are found to mediate the reductive amination of 3-amidocyclohexanones with divergent selectivity. Choice of peptide sequence can be used to alter the diastereoselectivity to favor either cis-product or trans-product, which are obtained in up to 93:7 er. NMR studies and DFT calculations are reported and indicate that both pathways rely on secondary interactions between substrate and catalyst to achieve selectivity. Furthermore, catalysts appear to accomplish a parallel kinetic resolution of the substrates...
March 16, 2018: Journal of Organic Chemistry
Yushu Jin, Yusuke Makida, Tatsuya Uchida, Ryoichi Kuwano
A chemoselective hydrogenation of isoquinoline carbocycles was achieved by using the catalyst prepared from Ru(methallyl)2(cod) and trans-chelate chiral ligand PhTRAP. The unique chemoselectivity achieved in this hydrogenation could be ascribed to the trans-chelation of the chiral ligand. The procedure for preparing the catalyst strongly affects the reproducibility of the carbocycle hydrogenation. Various 5-, 6-, 7-, and 8-substituted isoquinolines were selectively hydrogenated at their carbocycles to afford 5,6,7,8-tetrahydroisoquinolines as major products in high yields with moderate or good enantioselectivities...
March 16, 2018: Journal of Organic Chemistry
Haline G O Alvim, Jose Raimundo Correa, José A F Assumpção, Wender Alves da Silva, Marcelo Oliveira Rodrigues, Julio Lemos de Macedo, Mariana Fioramonte, Fabio Cesar Gozzo, Claudia C Gatto, Brenno A D Neto
The current manuscript describes the use of a heteropolyacid-containing task-specific ionic liquid, supported in imidazolium-based ionic liquids, as the catalyst for an efficient multicomponent synthesis of hexahydroimidazo[1,2-alpha]pyridine derivatives. The reactions conditions were fully optimized and the bridgehead nitrogen heterocycle derivatives could be obtained in just one hour exclusively as a single isomer (trans). Single crystal X-ray analysis confirmed the trans derivative as the only isomer. The mechanism of the reaction was investigated by ESI(+)-MS(/MS) and the use of the elegant charge-tag strategy allowed a catalytic cycle to be proposed for the current transformation and revealed the possibility of at least two reaction pathways...
March 16, 2018: Journal of Organic Chemistry
Vladimir V Voronin, Maria S Ledovskaya, Evgeniy G Gordeev, Konstantin S Rodygin, Valentine P Ananikov
A novel synthetic methodology for the preparation of 1,3-disubstituted pyrazoles from in situ generated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base. The other part is used to generate acetylene from CaC2 and water. Partitioning of the reactants improves the yields of desired pyrazoles up to 99% and simplifies their isolation to a simple procedure of solvent evaporation...
March 16, 2018: Journal of Organic Chemistry
Masao Morita, Yuichi Kobayashi
The stereoselective synthesis of resolvin D4 (RvD4) was achieved using the Wittig reaction of the C1-C10 dienal with the known C11-C22 phosphonium salt. The (S,E)-enantiomer (S)-10, corresponding to the C1-C8 part, was synthesized in 95% ee by the asymmetric transfer hydrogenation reaction of the corresponding acetylenic ketone followed by Red-Al reduction. Sharpless epoxidation of this alcohol using Ti(O-i-Pr)4/L-(+)-DIPT as a catalyst produced anti epoxy alcohol with >99% ee as the sole product in 82% yield...
March 16, 2018: Journal of Organic Chemistry
Linfeng Cui, Yang'en You, Xueling Mi, Sanzhong Luo
Asymmetric fluorination of α-branched aldehydes catalyzed by chiral primary amines under mild conditions has been developed. Both enantiomers could be obtained with good yields (up to 96%) and high enantioselectivity (up to 90% ee) by a simple swap of the fluorination reagent.
March 16, 2018: Journal of Organic Chemistry
Laura Castoldi, Laura Ielo, Wolfgang Holzer, Gerald Giester, Alexander Roller, Vittorio Pace
Primary and secondary α-halomethyl diazoketones generated via Arndt-Eistert chemistry with minimum loading of diazomethane efficiently alkylate aromatic amines in the presence of calcium oxide to furnish the corresponding α-arylamino diazoketones under full chemocontrol. Such a simple inorganic acid scavenger fully neutralizes the hydrohalic acid formed during the nucleophilic displacement which otherwise would immediately react to produce the corresponding α-haloketone. The methodology can be further exploited in analogous acylation-type processes on secondary arylamino diazoketones...
March 16, 2018: Journal of Organic Chemistry
Pengfei Zhang, Yu Zhou, Xu Han, Jinyi Xu, Hong Liu
The dearomatizing annulation reaction is a significant challenge in organic chemistry. The direct activation of α-carbons of simple saturated esters, as nucleophiles, is an important synthesis strategy. In the present study, we disclose [3+2] dearomatizing annulation reactions with direct activating α-carbons of saturated carboxylic esters and N-iminoisoquinolinium ylides, which possess highly enantioselective characteristics, catalyzed by N-heterocyclic carbenes (NHCs). The protocol achieves isoquinoline dearomatization and the construction of tricyclic chiral products under mild conditions with good yield, substrate tolerance, diastereoselectivity, and excellent enantioselectivity...
March 16, 2018: Journal of Organic Chemistry
Hengyao You, Srinivas Rao Vegi, Chandraiah Lagishetti, Shuo Chen, Rekula Santhosh Reddy, Xiaohong Yang, Jian Guo, Chenhui Wang, Yun He
A convenient synthesis of 3,4-dihydro-2H-naphtho [2,3-b] [1,4] oxazine-5,10-diones and 2,3,4,5-tetrahydro-1H-naphtho [2,3-b] azepine-6,11-diones via copper catalysed intramolecular C-O/C-C coupling reaction is described. This method showed good tolerance for functional groups and was applied to the synthesis of natural product core strcutures. Some coupling products exhibited moderate activities against lung cancer A549 cells.
March 16, 2018: Journal of Organic Chemistry
Huaiqing Zhao, Xi Zhou, Bo Li, Xiufen Liu, Ningxin Guo, Zhengliang Lu, Shoufeng Wang
Rh(III)-catalyzed C(sp3)-H bond aminocarbonylation of 8-methylquinolines and isocyanates has been realized under mild conditions. This approach is applicable to different aryl and alkyl isocyanates, leading to the synthesis of various α-quinolinyl amide compounds in moderate to excellent yields. A plausible mechanism for this transformation is proposed according to the experimental results obtained.
March 16, 2018: Journal of Organic Chemistry
Daniel C Crowley, Denis Lynch, Anita R Maguire
Enantioselective intramolecular Buchner reactions of α-diazoketones can be effected using heterogeneous copper-bis(oxazoline) catalysts in batch or using continuous flow processing in up to 83% ee. The catalyst can be reused up to 7 times without loss of activity. For α-diazoketones 3 and 4, the enantioselection achieved in flow with the immobilized catalyst was comparable with the standard homogeneous catalyzed process.
March 15, 2018: Journal of Organic Chemistry
Florian Glaus, Darija Dedic, Priyanka Tare, Valakunja Nagaraja, Liliana Rodrigues, Jose A Ainsa, Jens Kunze, Gisbert Schneider, Ruben C Hartkoorn, Stewart T Cole, Karl-Heinz Altmann
Described is the total synthesis of the myxobacterial natural product ripostatin B and of a small number of analogs. Ripostatin B is a polyketide-derived 14-membered macrolide that acts as an inhibitor of bacterial RNA-polymerase, but is mechanistically distinct from rifamycin-derived RNA-polymerase inhibitors that are in use for tuberculosis treatment. The macrolactone ring of ripostatin B features two stereocenters and a synthetically challenging doubly skipped triene motif, with one of the double bonds being in conjugation with the ester carbonyl...
March 15, 2018: Journal of Organic Chemistry
Sindhu Kancherla, Marianne Lorentzen, Victor Snieckus, Kåre Bredeli Jørgensen
A general method for the regioselective synthesis of a series of ortho-substituted chrysenyl N,N-diethyl-O-carbamates by the directed ortho metalation (DoM) strategy is reported. The starting O-carbamates were prepared from corresponding chrysenols, available by oxidative photochemical cyclization or directed remote metalation tactics. Chrysen-1-yl and chrysene-3-yl ring site selectivity of directed ortho metalation (DoM) and anionic ortho Fries rearrangement (AoF) protocols, with s-BuLi/TMEDA, followed by electrophilic quench using a selection of electrophiles, were observed leading to new chrysenyl derivatives...
March 15, 2018: Journal of Organic Chemistry
Raghavendra Achary, In-A Jung, Hyeon-Kyu Lee
A tandem process, involving Rh(III)-catalyzed oxidative C-H olefination of enantiomerically enriched 4-aryl-benzo-1,3-sulfamidates and subsequent intramolecular aza-Michael cyclization has been developed. The reaction produces trans-benzosulfamidate-fused-1,3-disubstituted isoindolines as major products, in which the configurational integrity of the stereogenic center in the starting material is preserved. Further transformations of the benzosulfamidate-fused-1,3-disubstituted isoindolines are described.
March 15, 2018: Journal of Organic Chemistry
Jeffrey Bruffaerts, Alexandre Vasseur, Sukhdev Singh, Ahmad Masarwa, Dorian Didier, Liron Oskar, Lionel Perrin, Odile Eisenstein, Ilan Marek
Several approaches using organozirconocene species for the remote cleavage of strained three-membered ring carbocycles are de-scribed. omega-Ene polysubstituted cyclopropanes, alkylidenecyclopropanes, omega-ene spiro[2.2]pentanes and omega-ene cyclopropyl methyl ethers were successfully transformed into stereodefined organometallic intermediates allowing an easy access to highly stereoen-riched acyclic scaffolds in good yields and in most cases excellent selectivities. DFT calculations and isotopic labeling experi-ments were performed to delineate the origin of the obtained chemo- and stereoselectivities, demonstrating the importance of microreversibility...
March 14, 2018: Journal of Organic Chemistry
Eietsu Hasegawa, Norihiro Izumiya, Tomoaki Miura, Tadaaki Ikoma, Hajime Iwamoto, Shin-Ya Takizawa, Shigeru Murata
Benzimidazolium naphthoxide (-ONap-BI+) was first synthesized and utilized as an unprecedented betaine photo-redox catalyst. Photoexcited state of -ONap-BI+ generated by visible light irradiation catalyzes the reductive deiodination as well as desulfonylation reactions in which 1,3-dimethyl-2-phenylbenzimidazoline (Ph-BIH) cooperates with as an electron and hydrogen atom donor. Significant solvent effects on the reaction progress were discovered and specific solvation toward imidazolium and naphthoxide moieties of -ONap-BI+ was proposed...
March 14, 2018: Journal of Organic Chemistry
Jaime Gracia-Vitoria, Iñaki Osante, Carlos Cativiela, Pedro Merino, Tomas Tejero
Enantiopure 2-thia-4-azabicyclo[3.1.0]hexanes, which can be considered constrained cysteines, have been obtained from L-cysteine by application of the "self-regeneration of chirality" concept. The key intermediates are homochiral thiazolines that can be prepared in multigram scale and react smoothly with a series of diazoalkanes providing Δ1-pyrazolines except for phenyldiazomethane that yield the isomeric Δ2-pyrazolines. Nitrogen extrusion in Δ1-pyrazolines and further reduction of the sulfinyl group yielded the target compounds in good overall yield...
March 14, 2018: Journal of Organic Chemistry
Xinzhe Shi, Shuxin Mao, Jean-François Soulé, Henri Doucet
The higher reactivity of C4-H bond as compared to C5-H bond of 1,2,3-trifluorobenzene in palladium-catalyzed direct arylation allows the selective synthesis of 4-aryl-1,2,3-trifluorobenzenes in moderate to high yields. In most cases, phosphine-free Pd(OAc)2 catalyst and inexpensive KOAc base were employed. Then, from these 4-aryl-1,2,3-trifluorobenzenes, the palladium-catalyzed C-H bond functionalization of the C6-position allows the synthesis of the corresponding 4,6-diarylated 1,2,3-trifluorobenzenes. We also applied these reaction conditions to the regioselective direct C3-arylation of 1,2,4-trifluorobenzene...
March 14, 2018: Journal of Organic Chemistry
Mahboubeh Kheirabadi, Gardner S Creech, Jennifer X Qiao, David S Nirschl, David K Leahy, Kenneth M Boy, Percy H Carter, Martin D Eastgate
Macrocyclic peptides containing N-alkylated amino acids have emerged as a promising therapeutic modality, capable of modulating protein-protein interactions and intracellular delivery of hydrophilic payloads. While multi-channel automated Solid Phase Peptide Synthesis (SPPS) is a practical approach for peptide synthesis, the requirement for slow and inefficient chromatographic purification of the product peptides is a significant limitation to exploring these novel compounds. Herein, we invent a "catch-release" strategy for the non-chromatographic purification of macrocyclic peptides...
March 14, 2018: Journal of Organic Chemistry
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"