Furo[3,4-b]chromones, and not Pyrano[3,4-b]chromones, are Obtained by the Reaction of 3-Formylchromones with Isocyanides
Contributors: Neo, Ana, Garrido, Leda, Díaz, Jesús, Marcaccini, Stefano, Marcos, Carlos
... Abstract The reaction of formylchromones with alkyl isocyanides was reinvestigated. In earlier reports from other research groups, two different structures were proposed for the products of this reaction. Herein, we provide unambiguous evidence that these products are chromenylmethylene furochromenones and not pyranochromones. Our structure assignment is based on X-ray diffraction analysis and two-dimensional NMR methods. The knowledge of the correct structure of these compounds is essential for the design of derivatives with potential applications as bioactive molecules or fluorescent biomarkers.
Contributors: Samanta, Rajarshi, Kulikov, Katharina, Strohmann, Carsten, Antonchick, Andrey
... Abstract An efficient novel protocol for the construction of an hyellazole-inspired compound collection is described. Starting from 2,6-diarylacetanilides, the desired products were obtained using hypervalent iodine promoted electrocyclization. The mechanism of product formation was investigated through intramolecular competition experiments.
Tandem Nucleophilic Addition/Fragmentation of Vinylogous Acyl Nonaflates for the Synthesis of Functionalized Alkynes, with New Mechanistic Insight
Contributors: Batsomboon, Paratchata, Gold, Brian, Alabugin, Igor, Dudley, Gregory
... Abstract Vinylogous acyl nonaflates, like the corresponding triflates, are subject to nucleophile-triggered fragmentation as part of a tandem process for generating functionalized alkynes. Advantages to the use of nonaflates in lieu of triflates include cost and stability. Computational analysis supports a postulated fragmentation mechanism involving a closed (cyclic) transition state with concerted extrusion of lithium sulfonate.
A Novel and Highly Regioselective Route to Construct Methylthio-Substituted Pyridazines from Aryl Methyl Ketones at Room Temperature
Contributors: Wu, Liuming, Yang, Yan, Gao, Meng, Zhang, Dongxue, Shu, Wenming, Zhu, Yanping, Wu, Anxin
... Abstract A novel and highly regioselective two-step homocoupling/cyclization procedure from easily available aryl methyl ketones and hydrazine hydrate was developed for the synthesis of methylthio-substituted pyridazines at room temperature. The method has remarkable advantages owing to the simple substrates, mild reaction conditions, ease of manipulation, good yields and high regioselectivity.
Contributors: Lisboa, Marilda, Jeong-Im, Jeannie, Jones, David, Dudley, Gregory
... Abstract Asymmetric synthesis of C16–C24 of palmerolide A is described, featuring convergent Negishi coupling, Singaram propargylation, and successful tactical maneuvering to address an unexpected allylic substitution reaction.
Contributors: Jarowicki,Krzysztof, Kocieński,Philip, Komsta,Zofia, Wojtasiewicz, Anna
... Abstract 1,2-Metallate rearrangements involving reaction of 1-metallated glycals with organolithium reagents under copper(I) mediation give alkenylpolyol chains in 45-91% yield (19 examples). The reaction was applied to a formal synthesis of KRN7000 as well as a synthesis of a Δ5,6-ceramide derivative.
Total Synthesis of d-lyxo-Phytosphingosine and Formal Synthesis of Pachastrissamine via a Chiral 1,3-Oxazine
Contributors: Mu, Yu, Kim, Ji-Yeon, Jin, Xiangdan, Park, Seok-Hwi, Joo, Jae-Eun, Ham, Won-Hun
... Abstract Concise and efficient syntheses of d-lyxo-phytosphingosine and pachastrissamine were achieved utilizing a chiral oxazine. The key features in these strategies are the stereoselective intramolecular oxazine formation catalyzed by palladium(0), and intermolecular olefin cross-metathesis.
Synthesis of Unsymmetrically Substituted 4,6,10-Trihydroxy-1,4,6,10-tetraazaadamantanes via Intramolecular Cyclization of Tris(β-oximinoalkyl)amines
Contributors: Semakin, Artem N., Sukhorukov, Alexey Yu., Nelyubina, Yulia V., Ioffe, Sema L., Tartakovsky, Vladimir A.
... Abstract The cyclotrimerization of oximino groups in unsymmetrically substituted tris(β-oximinoalkyl)amines was studied. A general approach to the synthesis of 4,6,10-trihydroxy-1,4,6,10-tetraazaadamantanes containing different substituents at bridgehead carbon atoms was developed from available aliphatic nitro compounds.
Synthesis of 3-Aroyl-4-hydroxy-4-arylpiperidine Derivatives by DBU-Catalyzed Reactions of Amines with Vinyl Ketones
Contributors: Liu, Xiaodong, Chen, Qiao, Li, Wenyi, Liang, Yuan, Wang, Rui
... Abstract In one-pot cascade reaction, a series of functionalized 3-aroyl-4-hydroxy-4-arylpiperidine derivatives were prepared from sulfonamides and vinyl ketones with good to excellent yields and diastereoselectivities. The reaction was catalyzed by the commercially available Lewis base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and could be easily manipulated under mild condition.
Contributors: Ji, Fei, Sun, Mu, Lv, Mei-fang, Yi, Wen-bin, Cai, Chun
... Abstract A new route for the synthesis of novel spirooxindoles from isocyanides, dialkyl acetylenedicarboxylates, and N-substituted isatylidene derivatives through [3+2] cycloaddition has been developed. This method has several advantages, such as high regioselectivity, high yields, readily available starting materials, and one-pot operations. The synthetic alkyne-containing spirooxindoles could also be used in the selective synthesis of triazole-containing spirocyclic compounds using a copper azide–alkyne cycloaddition (CuAAC) reaction.