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A practical, metal-free, and highlychemoselective approach wasdeveloped for the synthesis of ortho-CHO diaryl ethersby a three-component sequential coupling of arynes, N,N-dimethylformamide (DMF), and diaryliodoniumsalts. Diverse functional groups including halo, nitryl, and bulkysubstituents and heteroaromatics are well tolerated. Mechanistically,isotopic tracer experiments reveal that the diaryliodonium salt servesas an electrophile to trap the transient intermediates generated fromthe [2 + 2] cyclization of an aryne and DMF. [ABSTRACT FROM AUTHOR]

A Brønstedacid accelerated Pd-catalyzed asymmetric allylicalkylation of azlactones with simple allylic alcohols under mild reactionconditions has been realized, which provides a direct and readilyscalable approach for the synthesis of all-carbon quaternary allylicamino acid derivatives in excellent yields and good enantioselectivities. [ABSTRACT FROM AUTHOR]

Two approaches involving intramolecular and intermolecular cyclization, respectively, have been developed for the direct and practical construction of a series of important benzo[ f ]pyrrolo[1,2- a ][1,4]azepines by using Brønsted acid catalysts. Upon catalysis by TsOH, the intramolecular dehydroxylation/ring closure of 3-hydroxy-2-[2-(1 H -pyrrol-1-yl)benzyl]isoindolin-1-ones provided various racemic benzo[ f ]pyrrolo[1,2- a ][1,4]azepines in high yields. Furthermore, enantioenriched benzo[ f ]pyrrolo[1,2- a ][1,4]azepines were also obtained by chiral phosphoric acid catalyzed intermolecular addition of [2-(1 H -pyrrol-1-yl)phenyl]methanamines to 2-formylbenzoates under mild conditions. [ABSTRACT FROM AUTHOR]

A novel process involving base-catalyzed intramolecular defluorination/O-arylation of readily available α-fluoro-β-one-sulfones was realized and provided a series of 3-fluoro-1,4-oxathiine 4,4-dioxide derivatives in good to excellent yields. Unlike traditional defluorination reactions with stoichiometric base as the deacid reagent, this process is triggered by a catalytic amount of base (TMG: tetramethylguanidine) and molecular sieves serve as both an adsorbent to remove HF acid and an activator to assist C–F bond cleavage. [ABSTRACT FROM AUTHOR]

Despite the widespread use of naphthamide atropisomers in biologically active compounds and asymmetric catalysis, few catalytic methods have succeeded in the enantioselective synthesis of these compounds. Herein, a chiral Brønsted acid (CBA) catalysis strategy was developed for readily scalable dynamic kinetic resolution of challenging ortho-formyl naphthamides with pyrrolylanilines. The chiral axis of the atropisomeric amide and a stereogenic center were simultaneously established for a new family of potential biologically active pyrrolopyrazine compounds with high enantio- and diastereoselectivities (up to >20 : 1 d.r. and 98 : 2 e.r.). Epimerization experiments of its derivatives reveal that the N-substitution of the nearby stereogenic center could affect the configurational stability of the axially chiral aromatic amides. These results might be useful for the construction of other kinds of novel axially chiral molecules with a low rotational barrier. [ABSTRACT FROM AUTHOR]

A Chiral Brønsted acid catalyzed asymmetric intramolecular ring‐closing alkylation of inert pyrroles with α, β‐unsaturated ketones has been developed. This approach gave a wide range of 4‐phenyl‐4,5‐dihydro‐6H‐benzo[f]pyrrolo[1,2‐a]azepin‐6‐ones in high yields with good enantioselectivities under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The coupling between ortho-trimethylsilyl aryl triflates, N,N-dimethylformamide and diaryliodonium salts tolerates various functional groups. [ABSTRACT FROM AUTHOR]

Preliminary experiments towards an asymmetric allylation of (Ia) with (II) using chiral mono or diphosphine ligands furnish (IIIa) with up to 17% enantiomeric excess only. [ABSTRACT FROM AUTHOR]

The first efficient example of the direct allylic alkylation of azlactones with simple allylic alcohols using only Pd(PPh3)4 as catalyst under neutral conditions by substrate self-assisted activation strategy is reported. [ABSTRACT FROM AUTHOR]

A highly enantioselective regiodivergent addition of alkoxyallenes to pyrazolones was developed to afford multiply functionalized alkylated products bearing a quaternary carbon stereocenter in high yields with excellent stereoselectivities. One approach is enabled by palladium catalysis, thus leading to branched allylic pyrazol-5-ones under mild reaction conditions. The other is catalyzed by a chiral Brønsted acid to give linear products exclusively. Moreover, the usefulness of this new method was highlighted by converting the allylic products into other interesting multifunctionalized pyrazolone derivatives which would be of great potential for the exploitation of pharmaceutically important molecules. [ABSTRACT FROM AUTHOR]

A highly enantioselective regiodivergent addition of alkoxyallenes to pyrazolones was developed to afford multiply functionalized alkylated products bearing a quaternary carbon stereocenter in high yields with excellent stereoselectivities. One approach is enabled by palladium catalysis, thus leading to branched allylic pyrazol-5-ones under mild reaction conditions. The other is catalyzed by a chiral Brønsted acid to give linear products exclusively. Moreover, the usefulness of this new method was highlighted by converting the allylic products into other interesting multifunctionalized pyrazolone derivatives which would be of great potential for the exploitation of pharmaceutically important molecules. [ABSTRACT FROM AUTHOR]

A new approach has been established for Rh(iii)-catalyzed direct aza oxidative cyclization of non-prefunctionalized azobenzenes to provide 2-aryl-2H-benzotriazoles in good yields, in which AgNO3 instead of conventional azide reagents for the first time functions as the nitrogen source for the nitrogenation reaction. Preliminary mechanistic studies suggest that the Rh(iii)-catalyst could account for the nitration reaction, and subsequently cationic silver species might both play a vital role in the fission of the nitrogen–oxygen bonds in nitro groups and promote aza oxidative cyclization. [ABSTRACT FROM AUTHOR]

The title reaction gives aryl substituted naphthalenes as products [e.g. (III)] and tolerates various functional groups. [ABSTRACT FROM AUTHOR]

A mass spectrometric study of protonated warfarin and its derivatives (compounds 1 to 5) has been performed. Losses of a substituted benzylideneacetone and a 4-hydroxycoumarin have been observed as a result of retro-Michael reaction. The added proton is initially localized between the two carbonyl oxygens through hydrogen bonding in the most thermodynamically favorable tautomer. Upon collisional activation, the added proton migrates to the C-3 of 4-hydroxycoumarin, which is called the dissociative protonation site, leading to the formation of the intermediate ion-neutral complex (INC). Within the INC, further proton transfer gives rise to a proton-bound complex. The cleavage of one hydrogen bond of the proton-bound complex produces the protonated 4-hydroxycoumarin, while the separation of the other hydrogen bond gives rise to the protonated benzylideneacetone. Theoretical calculations indicate that the 1, 5-proton transfer pathway is most thermodynamically favorable and support the existence of the INC. Both substituent effect and the kinetic method were utilized for explaining the relative abundances of protonated 4-hydroxycoumarin and protonated benzylideneacetone derivative. For monosubstituted warfarins, the electron-donating substituents favor the generation of protonated substituted benzylideneacetone, whereas the electron-withdrawing groups favor the formation of protonated 4-hydroxycoumarin. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Ligand exchange reactions of [Ni2+ M (SCH3)−]+ (m/z 315, CI-a), (M=ArCH=NNHC(=S)SCH3), with the residual ESI solvent molecules in the ion trap have been investigated by electrospray ionization (ESI) mass spectrometry and quantum calculation. The intermediates, including [Ni2+ M (SCH3)− (CH3CN)]+ (m/z 356) and [Ni2+ (M−H)−]+ (m/z 267), in both the associative and the dissociative pathways have been obtained in the tandem MS, indicating that the two mechanistic pathways are efficient in the ligand exchange reactions. The electronic effect of the phenyl substituent on the reactivity of [Ni2+ (M*−H)−]+ has also been investigated by mass selection in the MS4 experiments. Intra-complex proton transfer to the anion ligand (SCH3)− is essential for the ligand exchange reactions. D-labeling experiments confirmed that the transferring proton comes from either the thioamide proton, or the phenyl proton via Csp2-H activation leading to cyclometallated complexes. DFT calculations at uB3LYP/6-31+G(2d, p) level gave the key species and the potential energy surfaces for the model reaction system of CI-a and acetonitrile. [Copyright &y& Elsevier]

The back cover of the journal "Angewandte Chemie International Edition" is presented.

Zwei katalytische Prozesse …… , nämlich Palladium ‐ Katalyse und Brønsted ‐ Säure ‐ Katalyse, liefern unterschiedliche Produkte bei der Addition von Alkoxyallenen an Pyrazolone. Wie G. Jiang et al. in ihrer Zuschrift auf S. 1097 zeigen, führt Pd ‐ Katalyse zu verzweigten allylischen Pyrazol ‐ 5 ‐ onen unter extrem milden Bedingungen, während eine chirale Brønsted ‐ Säure lineare Additionsprodukte ergibt. [ABSTRACT FROM AUTHOR]

Broensted acid Tf2NH catalyzes Friedel-Crafts type head-to-tail hydroalkenylation and hydroarylation of vinylarenes [(I), (III), (V), and (VII)] under mild reaction conditions providing a readily scalable, metal-free, and practical access to bioactive trans-1,3-diaryl-1-butenes [(II), (IV), and (IX)] and cyclic analogues [(VI) and (VIII)] and 1,1-diarylalkanes (XI), resp., in high regioselectivity. [ABSTRACT FROM AUTHOR]

Broensted acid Tf2NH catalyzes Friedel-Crafts type head-to-tail hydroalkenylation and hydroarylation of vinylarenes [(I), (III), (V), and (VII)] under mild reaction conditions providing a readily scalable, metal-free, and practical access to bioactive trans-1,3-diaryl-1-butenes [(II), (IV), and (IX)] and cyclic analogues [(VI) and (VIII)] and 1,1-diarylalkanes (XI), resp., in high regioselectivity. [ABSTRACT FROM AUTHOR]

The article presents chemical equations for article "AgNO3 as Nitrogen Source for Rhodium(III)-Catalyzed Synthesis of 2-Aryl-2H-benzotriazoles from Azobenzenes" by J. Li and others, published in "Chemical Communications" in 2016.

Vinyl cyclopropanes can be utilized as very effective reactants in the Pd(0)-catalyzed allylic alkylation for quickly assembling an all-carbon quaternary allylic center at the 3-position of oxindole in good yields and with excellent regioselectivities. [ABSTRACT FROM AUTHOR]