NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones

Thiazolium carbene-catalyzed reactions of 1,2-diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave α,β-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products

Stoichiometric and catalytic C-C and C-H bond formation with B(C6F5)3 via cationic intermediates

This work showcases a new catalytic cyclization reaction using a highly Lewis acidic borane with concomitant C−H or C−C bond formation. The activation of alkyne‐containing substrates with B(C6F5)3 enabled the first catalytic intramolecular cyclizations of carboxylic acid substrates using this Lewis acid. In addition, intramolecular cyclizations of esters enable C−C bond formation as catalytic B(C6F5)3 can be used to effect formal 1,5‐alkyl migrations from the ester functional groups to unsaturated carbon–carbon frameworks. This metal‐free method was used for the catalytic formation of complex dihydropyrones and isocoumarins in very good yields under relatively mild conditions with excellent atom efficiency

Stöchiometrische und katalytische C-C- und C-H-Bindungsbildung mit B(C6 F5 )3 über kationische Zwischenstufen

Diese Arbeit beschreibt eine neuartige katalytische Cyclisierung unter Verwendung eines stark Lewis-sauren Borans mit einhergehender C-H- oder C-C-Bindungsbildung. Die Aktivierung von Molekülen mit C-C-Dreifachbindungen unter Verwendung von B(C6F5)3 ermöglicht erstmals eine entsprechende Lewis-Säure-katalysierte, intramolekulare Cyclisierung von Carbonsäuren. Darüber hinaus zeigen die Ester dieser Carbonsäuren mit katalytischen Mengen B(C6F5)3 eine formale 1,5-Migration der Estergruppen unter Knüpfung einer C-C-Bindung. Unter Verwendung dieser neuen metallfreien Methode konnten anspruchsvolle Dihydropyrone und Isocumarine in hohen Ausbeuten unter milden Bedingungen sowie mit hoher Atomökonomie synthetisiert werden

NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones

Thiazolium carbene-catalyzed reactions of 1,2-diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave α,β-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products

Palladium-catalyzed heteroallylation of unactivated alkenes – synthesis of citalopram

A palladium-catalyzed difunctionalization of unactivated alkenes with tethered nucleophiles is reported. The versatile reaction occurs with simple allylic halides and can be carried out under air. The methodology provides rapid access to a wide array of desirable heterocyclic targets, as illustrated by a concise synthesis of the widely prescribed antidepressant citalopram

Neutral and Cationic Rare Earth Metal Alkyl and Benzyl Compounds with the 1,4,6-Trimethyl-6-pyrrolidin-1-yl-1,4-diazepane Ligand and Their Performance in the Catalytic Hydroamination/Cyclization of Aminoalkenes

A new neutral tridentate 1,4,6-trimethyl-6-pyrrolidin-1-yl-1,4-diazepane (L) was prepared. Reacting L with trialkyls M(CH2SiMe3)3(THF)2 (M = Sc, Y) and tribenzyls M(CH2Ph)3(THF)3 (M = Sc, La) yielded trialkyl complexes (L)M(CH2SiMe3)3 (M = Sc, 1; M = Y, 2) and tribenzyl complexes (L)M(CH2Ph)3 (M = Sc, 3; M = La, 4). Complexes 1 and 2 can be converted to their corresponding ionic compounds [(L)M(CH2SiMe3)2(THF)][B(C6H5)4] (M = Sc, Y) by reaction with [PhNMe2H][B(C6H5)4] in THF. Complexes 3 and 4 can be converted to cationic species [(L)M(CH2Ph)2]+ by reaction with [PhNMe2H][B(C6F5)4] in C6D5Br in the absence of THF. The neutral complexes 1-4 and their cationic derivatives were studied as catalysts for the hydroamination/cyclization of 2,2-diphenylpent-4-en-1-amine and N-methylpent-4-en-1-amine reference substrates and compared with ligand-free Sc, Y, and La neutral and cationic catalysts. The most effective catalysts in the series were the cationic L-yttrium catalyst (for 2,2-diphenylpent-4-en-1-amine) and the cationic lanthanum systems (for N-methylpent-4-en-1-amine). For the La catalysts, evidence was obtained for release of L from the metal during catalysis.

Employing Relative Entropy Techniques for Assessing Modifications in Animal Behavior

In order to make quantitative statements regarding behavior patterns in animals, it is important to establish whether new observations are statistically consistent with the animal's equilibrium behavior. For example, traumatic stress from the presence of a telemetry transmitter may modify the baseline behavior of an animal, which in turn can lead to a bias in results. From the perspective of information theory such a bias can be interpreted as the amount of information gained from a new measurement, relative to an existing equilibrium distribution. One important concept in information theory is the relative entropy, from which we develop a framework for quantifying time-dependent differences between new observations and equilibrium. We demonstrate the utility of the relative entropy by analyzing observed speed distributions of Pacific bluefin tuna, recorded within a 48-hour time span after capture and release. When the observed and equilibrium distributions are Gaussian, we show that the tuna's behavior is modified by traumatic stress, and that the resulting modification is dominated by the difference in central tendencies of the two distributions. Within a 95% confidence level, we find that the tuna's behavior is significantly altered for approximately 5 hours after release. Our analysis reveals a periodic fluctuation in speed corresponding to the moment just before sunrise on each day, a phenomenon related to the tuna's daily diving pattern that occurs in response to changes in ambient light

Two-way habitat use between reefs and open ocean in adult greater amberjack: evidence from biologging data

We investigated the relationships between vertical movements and both oceanographic features and physiological factors in greater amberjack Seriola dumerili, which is a reef-associated predator in the East China Sea. S. dumerili in the coastal waters of eastern Taiwan were equipped with archival tags or pop-up satellite archival tags that recorded depth and temperature, resulting in a dataset covering a total of 1331 d from 12 individuals. To classify the vertical movement patterns of S. dumerili, we performed a hierarchical cluster analysis for the depth profile. We observed multiple vertical movement patterns. Around topographic features, S. dumerili showed short-step dives (averaging < 35 m) during both the daytime and nighttime. In contrast, S. dumerili in offshore areas showed diel vertical movements. S. dumerili occasionally performed frequent dives to approximately 150 m throughout the day. These movements may be related to foraging behaviors associated with changes in water depth. We further analyzed the response of the peri-toneal cavity temperature to variations in the ambient temperature in 7 S. dumerili with archival tags. The peritoneal cavity temperatures fluctuated according to the ambient temperature changes, indicating that the vertical movement of S. dumerili is limited by physiological con-straints for the maintenance of body temperature. Together, our results indicate that the vertical movement of S. dumerili may be affected by the trade-off between foraging and thermoregulation

Gold(I)-Catalyzed Cycloisomerizations and Alkoxycyclizations of ortho-(Alkynyl)styrenes

Indenes and related polycyclic structures have been efficiently synthesized by gold(I)-catalyzed cycloisomerizations of appropriate ortho-(alkynyl)styrenes. Disubstitution at the terminal position of the olefin was demonstrated to be essential to obtain products originating from a formal 5-endo-dig cyclization. Interestingly, a complete switch in the selectivity of the cyclization of o-(alkynyl)-α-methylstyrenes from 6-endo to 5-endo was observed by adding an alcohol to the reaction media. This allowed the synthesis of interesting indenes bearing an all-carbon quaternary center at C1. Moreover, dihydrobenzo[a]fluorenes can be obtained from substrates bearing a secondary alkyl group at the β-position of the styrene moiety by a tandem cycloisomerization/1,2-hydride migration process. In addition, diverse polycyclic compounds were obtained by an intramolecular gold-catalyzed alkoxycyclization of o-(alkynyl)styrenes bearing a nucleophile in their structure. Finally, the use of a chiral gold complex allowed access to elusive chiral 1H-indenes in good enantioselectivitiesMinisterio de Economia y Competitividad (MINECO) and FEDER (CTQ2010-15358 and CTQ2013-48937-C2-1-P) and Junta de Castilla y Leon (BU237U13) for financial support. A.M.S. thanks the Junta de Castilla y Leon (Consejeria de Educacion) and the Fondo Social Europeo for a PIRTU contract. M.A.R. and P.G.-G. thank MEC for a "Young Foreign Researchers" (SB2009-0186) contract and MINECO for "Juan de la Cierva" contract, respectivelyThis is the peer reviewed version of the following article: Sanjuán, A. M., Rashid, M. A., García-García, P., Martínez-Cuezva, A., Fernández-Rodríguez, M. A., Rodríguez, F. and Sanz, R. (2015), Gold(I)-Catalyzed Cycloisomerizations and Alkoxycyclizations of ortho-(Alkynyl)styrenes. Chem. Eur. J., 21: 3042–3052. doi: 10.1002/chem.201405789, which has been published in final form at 10.1002/chem.201405789. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archivin