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Journal of Organic Chemistry

Shota Nomiyama, Takahiro Ogura, Hiroaki Ishida, Kazuki Aoki, Teruhisa Tsuchimoto
Treatment of N-substituted pyrroles with carbonyl compounds and nucleophiles under indium catalysis was found to be a promising method for preparing β-alkylpyrroles without contamination by α-alkylpyrroles. With this methodology, a variety of alkyl groups, which are primary, secondary and tertiary as well as cyclic and functionalized types, can be introduced in place onto the pyrrole ring. The simplicity performable as a catalytic one-step process is one of the important feature of this reaction. The substituent on the nitrogen atom of the product β-alkylpyrrole can be removed easily by literature procedures...
March 23, 2017: Journal of Organic Chemistry
Keshab Mondal, Subhas Chandra Pan
A convenient synthesis of 2,5-disubstituted furan has been developed by employing donor-acceptor oxiranes in a new reaction with γ-hydroxyenones. Sc(OTf)3 was found to be the best catalyst and 2,5-disubstituted furans are obtained in moderate to good yields under mild reaction conditions. The scope of the reaction is quite decent allowing for the synthesis of disubstituted furans having aryl and heteroaromatic groups.
March 23, 2017: Journal of Organic Chemistry
Anupam Jana, Kasjan Misztal, Anna Zak, Karol Grela
A strategy for the synthesis of functionalised indenes is presented. The readily available substituted phenols are used as starting materials in the reaction sequence composed of Pd-catalysed Suzuki coupling and Ru-catalysed ring-closing metathesis, thus representing a practical method for the controlled construction of functionalized indene derivatives. The methodology has been successfully applied to a broad range of substrates, producing substituted indenes in excellent yields. This approach is also utilized for the synthesis of substituted indenes selectivity deuterated in position 3, which are rare in literature...
March 23, 2017: Journal of Organic Chemistry
Lisha Wu, Yinfeng Meng, Jamie Ferguson, Lijie Wang, Fanlong Zeng
Palladium-catalyzed oxidative annulation of ortho-alkenyllanilines and allenes to constitute valuable but synthetically challenging benzo[b]azepines has been developed. The procedure, involving of the cleavage of the terminal C(sp2)-H bond of the vinyl moiety and the participation of allenes as two-carbon cycloaddition partner, is attractive in terms of assembly efficiency and environmentally friendliness. The transformation features mild reaction conditions and good functional group tolerance, resulting in a variety of benzo[b]azepines in good to excellent yields...
March 23, 2017: Journal of Organic Chemistry
Eman Zawia, David J Hamnett, Wesley James Moran
The facile synthesis of stable enynyl- and dienyl(aryl)iodonium salts is achieved from terminal enynes. An X-ray crystal structure of an example of the latter is presented. These compounds are shown to be useful in a range of transformations.
March 23, 2017: Journal of Organic Chemistry
Tanmay Chatterjee, Da Seul Lee, Eun Jin Cho
Herein we report an extended study of [4 + 2] benzannulation reactions of 2-(hetero)aryl-substituted anilines with alkynes by visible light photocatalysis. The method requires the use of tBuONO as a diazotizing agent and 0.3 mol% of fac-Ir(ppy)3 as a photocatalyst at room temperature. The reaction proceeded in a chemo- and regioselective manner with high functional group tolerance under mild conditions allowing the preparation of a wide variety of polycyclic (hetero)aromatic compounds, including phenanthrenes, in moderate to high yields...
March 23, 2017: Journal of Organic Chemistry
Valeriy O Filimonov, Lidia N Dianova, Kristina A Galata, Tetyana V Beryozkina, Mikhail Sergeevich Novikov, Vera S Berseneva, Oleg S Eltsov, Albert T Lebedev, Pavel A Slepukhin, Vasiliy A Bakulev
Solvent-base-controlled, transition metal-free and high yield synthesis of 4,5-functionalized 1,2,3-thiadiazoles and 1,2,3-triazoles from 2-cyanothioacetamides and sulfonyl azides is described. Under diazo transfer conditions in the presence of a base in an aprotic solvent 2-cyanothioacetamides operating as C-C-S building blocks produce 5-amino-4-cyano-1,2,3-thiadiazoles exclusively. The use of alkoxide/alcohol system completely switches the reaction course due to the change of one of the reaction centers in the 2-cyanothioacetamide (C-C-N building block) resulting in the formation of 5-sulfonamido-1,2,3-triazole-4-carbothioamide sodium salts as the only products...
March 22, 2017: Journal of Organic Chemistry
Yan Liu, Huayou Hu, Xiang Wang, Sanjun Zhi, Yuhe Kan, Chao Wang
Pyrroles are an important group of heterocyclic compounds with a wide range of interesting properties, which have resulted in numerous applications in a variety of fields. Despite the importance of these compounds, there have been few reports in the literature pertaining to the synthesis of pyrroles from simple alkenes using a one-pot sequential 1,3-dipolar cycloaddition/aromatization reaction sequence. Herein, we report the development of a benzoyl peroxide-mediated oxidative dehydrogenative aromatization reaction for the construction of pyrrolidines...
March 22, 2017: Journal of Organic Chemistry
Jing Cao, Shuding Dong, Delu Jiang, Peiyu Zhu, Han Zhang, Rui Li, Zhanyi Li, Xuanyu Wang, Weifang Tang, Ding Du
β-Functionalization of indolin-2-one-derived aliphatic acids has been applied in formal [3+2] annualtions for catalyst-free and divergent synthesis of two series of structurally interesting 3, 3'-spirooxindole γ-butyrolactones that may be attractive for potential drug discovery. These findings also pave the way for further diversity-oriented synthesis of spirooxindoles starting from indolin-2-one-derived aliphatic acids or their derivatives.
March 22, 2017: Journal of Organic Chemistry
Denhy Hernández-Melo, Ruy Cervantes, Jorge Tiburcio
A stimulus-responsive guest containing spiropyran and viologen units assembles with a 24-membered crown ether into a stable host-guest complex displaying a partially threaded geometry. Acid addition induces guest transformation to a merocyanine species activating a second recognition site, suitable for the formation of a pseudorotaxane. The simultaneous presence of two recognition sites produces a small-amplitude macrocycle shuttling motion, from the viologen to the merocyanine moiety. Base addition returns the guest to its spiropyran form and concurrently the translation motion stops...
March 22, 2017: Journal of Organic Chemistry
Patrick G McCaw, Naomi M Buckley, Kevin S Eccles, Simon E Lawrence, Anita R Maguire, Stuart G Collins
Diazo transfer to β-keto sulfoxides to form stable isolable α-diazo-β-keto sulfoxides has been achieved for the first time. Both monocyclic and benzofused ketone derived β-keto sulfoxides were successfully explored as substrates for diazo transfer. Use of continuous flow leads to isolation of the desired compounds in enhanced yields relative to standard batch conditions, with short reaction times, increased safety profile, and potential to scale up.
March 22, 2017: Journal of Organic Chemistry
Arijit A Adhikari, Tamie Suzuki, Reesheda J Gilbert, Matthew R Linaburg, John Daniel Chisholm
The rearrangement of allylic trichloroacetimidates is a well-known transformation, but the corresponding rearrangement of benzylic trichloroacetimidates has not been explored as a method for the synthesis of benzylic amines. Conditions that provide the trichloroacetamide product from a benzylic trichloroacetimidate in high yield have been developed. Methods were also investigated to transform the trichloroacetamide product directly into the corresponding amine, carbamate and urea. A cationic mechanism for the rearrangement is implicated by the available data...
March 21, 2017: Journal of Organic Chemistry
Simone Albano, Giorgio Olivo, Luigi Mandolini, Chiara Massera, Franco Ugozzoli, Stefano Di Stefano
An imidazo[1,5-a]pyridine derivative was unexpectedly obtained through the action of Fe2+ on a dynamic library of imines generated in situ via condensation of benzaldehyde and 2-picolylamine. The reaction product was easily isolated as the only nitrogen-containing product eluted from the chromatographic column. A reaction mechanism is proposed, in which combined kinetic and thermodynamic effects exerted by Fe2+ on the various steps of the complex reaction sequence are discussed. The Fe2+ nature of the added metal cation was found to be pivotal for the achievement of the imidazo[1,5-a]pyridine derivative as well as its amount in the reaction mixture...
March 21, 2017: Journal of Organic Chemistry
Kota Nishino, Kohei Minato, Takahiro Miyazaki, Yohei Ogiwara, Norio Sakai
In this study an InI3-TMDS (1,1,3,3-tetramethyldisiloxane) reducing system effectively catalyzed the reductive dithioacetalization of a variety of aromatic and aliphatic carboxylic acids with 1,2-ethanedithiol or 1,3-propanedithiol leading to the one-pot preparation of either 1,3-dithiolane derivatives or a 1,3-dithiane derivative. Also, the intact indium catalyst continuously catalyzed the subsequent oxidative desulfurization of an in-situ formed 1,3-dithiolane derivative, which led to the preparation of the corresponding aldehydes...
March 21, 2017: Journal of Organic Chemistry
Fangzhou Wu, John P Mayer, Vasily G Gelfanov, Fa Liu, Richard D DiMarchi
Naturally-occurring, multiple cysteine-containing peptides are a structurally unique class of compounds with a wide range of therapeutic and diagnostic applications. The development of reliable, and precise chemical methods for their preparation is of paramount importance to facilitate exploration of their utility. We report an efficient approach based on stepwise, sequentially directed disulfide bond formation, exemplified here by the synthesis of four-disulfide bond containing insulin analogs. The cysteine protections consisted of tert-butylthiol (StBu), thiol-trimethoxyphenyl (STmp), trityl (Trt), 4-methoxytrityl (Mmt), S-acetamidomethyl (Acm) and tert-butyl (tBu)...
March 20, 2017: Journal of Organic Chemistry
Matthew N Grayson
We report density functional theory calculations which examine the mechanism and origins of stereoselectivity of Soós' landmark discovery from 2005 that cinchona thioureas catalyze the asymmetric Michael addition of nitroalkanes to enones. We show that the electrophile is activated by the catalyst's protonated amine and that the nucleophile binds to the thiourea moiety by hydrogen bonding. These results lead to the correction of published mechanistic work which did not consider this activation mode. We have also investigated the corresponding cinchona squaramide-catalyzed reaction and found that it proceeds by the same mechanism, despite the differences in the geometry of the two catalysts' hydrogen bond donating groups, which demonstrates the generality of this mechanistic model...
March 20, 2017: Journal of Organic Chemistry
Nezar Al-Bataineh, Kendall N Houk, Matthias Brewer, Xin Hong
Cationic 1-aza-2-azoniaallene salts react with structurally constrained alkenes in intramolecular reactions by C-H insertion at the allylic position, or by (2 + 1)-cycloaddition with the alkene followed by ring opening. The latter reaction gives further evidence of the nitrenium-like character of 1-aza-2-azoniaallene salts. DFT calculations show that alkene addition is intrinsically more favorable, but that predistortion can lead to C-H insertion.
March 20, 2017: Journal of Organic Chemistry
Liwei Zheng, Markus Griesser, Derek A Pratt, Marc M Greenberg
Formal hydrogen atom abstraction from the nitrogen-hydrogen bonds in purine nucleosides produces reactive intermediates that are important in nucleic acid oxidation. Herein we describe an approach for the independent generation of the purine radical resulting from hydrogen atom abstraction from the N6-amine of 2'-deoxyadenosine (dA•). The method involves sequential Norrish Type I photocleavage of a ketone (7b) and β-fragmentation of the initially formed alkyl radical (8b) to form dA• and acetone. The formation of dA• was followed by laser flash photolysis, which yields a transient with λmax ≈ 340 nm and a broader weaker absorption centered at ∼560 nm...
March 20, 2017: Journal of Organic Chemistry
Mao-Lin Fu, Jian-Bo Liu, Xiu-Hua Xu, Feng-Ling Qing
A silver triflate (AgOTf)-mediated oxidative pentafluoroethylation of alcohols and phenols with nucleophilic (pentafluoroethyl)trimethylsilane (TMSCF2CF3) using selectfluor as oxidant under mild reaction conditions was developed. This oxidative coupling protocol utilizes broadly available substrates and easily handled reagents to afford various pentafluoroethyl ethers in moderate to excellent yields. Furthermore, this method was extended to the oxidative heptafluoropropylation and ethoxycarbonyldifluoromethylation of alcohols and phenols for preparation of the corresponding fluoroalkyl ethers...
March 20, 2017: Journal of Organic Chemistry
Peng Yang, Xiao Wang, Feng Chen, Zheng-Bing Zhang, Chao Chen, Lin Peng, Li-Xin Wang
The first organocatalytic enantioselective Michael/cyclization domino reaction between 3-amideoxindoles and α,β-unsaturated aldehydes is described. After sequential oxidation with pyridinium chlorochromate, a direct and one-pot preparation of highly sterically hindered spirocyclic oxindole-γ-lactams was achieved in 51-81% yields with 75-97% ee and ≤80/20 dr.
March 20, 2017: Journal of Organic Chemistry
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