Abstract A novel reaction based on synergistic catalysis, combining palladium‐ and organocatalysis has been developed. The palladium catalyst activates vinyl benzoxazinanones via a decarboxylation to undergo [4+2] cycloaddition with iminium‐ion activated α,β‐unsaturated aldehydes. is demonstrated proceed for number of combinations reacting aldehydes, providing highly substituted tetrahydroquinolines in good high yields, excellent enantio‐ diastereoselectivities (>98 % ee >20:1 d.r.)....

The concept of pericyclic reactions and the explanation their specificity through orbital symmetries introduced a new way understanding looking for ones. One 1965 Woodward-Hoffmann communications described "the (as yet unobserved) symmetry-allowed 6 + 4 combination", prediction field "higher-order" cycloadditions, involving more than six electrons. Later these authors predicted exo-stereoselectivity [6 4]-cycloaddition. Chemists rushed to test this (for most part successfully). For half...

The development of the first chemo-, regio-, and stereoselective hetero-[6+4] -[6+2] cycloadditions heteroaromatic compounds via amino aza- diazafulvenes is presented. Pyrroles, imidazoles, pyrazoles substituted with a formyl group react an aminocatalyst to generate electron-rich hetero-6π-component that reacts in manner electron-deficient dienes olefins. For cycloaddition pyrrole system dienes, wide variation both reaction partners possible, providing attractive pyrrolo-azepine products...

A novel enantioselective (8+3) cycloaddition between donor-acceptor cyclopropanes and heptafulvenoids catalysed by a chiral bifunctional Brønsted base is described. Importantly, the reaction, which leverages an anionic activation strategy, divergent from prototypical Lewis-acid protocols. series of cyclopropylketones react with tropones affording desired cycloadducts in high yield enantiomeric excess. For barbiturate substituted heptafulvenes, proceeds good yield, excellent...

The mechanisms and origins of chemo- stereoselectivities the organocatalytic [6+4] cycloaddition between 2-cyclopentenone tropone have been investigated by a combined computational experimental study. In presence cinchona alkaloid primary amine catalyst an acid additive, forms cross-dienamine intermediate that subsequently undergoes stepwise reaction via zwitterionic intermediate. rate-determining transition state features strong hydrogen-bonding interaction oxygen atom protonated...

The cinchona-alkaloid-catalyzed cycloaddition reactions of 2-cyclohexenone with tropone and various heptafulvenes give [8+2] or [4+2] cycloadducts, depending on the substituents present heptafulvene. We report results new experiments heptafulvenes, containing diester barbiturate substituents, which in combination computational studies were performed to elucidate factors controlling vs pathways, including chemo-, regio-, stereoselectivities these higher-order cycloadditions. protonated...

The first atroposelective aminocatalytic methodology for the construction of C-N atropisomers is presented. synthesis this class axially chiral molecules typically encompasses substrates in which bond pre-formed. In contrast, work presents direct coupling indole-2-carboxaldehydes to ortho-quinones, form stereogenic axis an way. Application typical secondary amine catalysts furnished desired product, however, low yields and as a complex mixture arising from poor regiocontrol among C3 - N1...

We calculate the low-lying energy spectrum for three trapped identical bosons interacting via a finite-range potential. The is compared to results from zero-range model. thresholds trimer binding and atom-dimer are extracted related effective range corrections. Effective corrections Efimov physics Borromean two aspects of same effect, we connect these regions qualitatively. window becomes slightly narrower substantial ranges. structure at threshold an atom far away dimer major correction due...

We consider the stability of an ultracold trapped Bose-Einstein condensate near a Feshbach resonance. Using modified Gross-Pitaevskii equation that includes higher-order terms and multichannel model resonances, we find regions where can be enhanced or suppressed around experimentally measured resonances. suggest number ways to probe diagram. scattering length zero crossings huge deviations are found for critical particle number. Effects narrow resonances tighter traps. Macroscopic tunneling...

Abstract A novel reaction based on synergistic catalysis, combining palladium‐ and organocatalysis has been developed. The palladium catalyst activates vinyl benzoxazinanones via a decarboxylation to undergo [4+2] cycloaddition with iminium‐ion activated α,β‐unsaturated aldehydes. is demonstrated proceed for number of combinations reacting aldehydes, providing highly substituted tetrahydroquinolines in good high yields, excellent enantio‐ diastereoselectivities (>98 % ee >20:1 d.r.)....

The thermal dimerization of cycloheptatriene is predicted to occur by a concerted [6 + 4] cycloaddition via an ambimodal 4]/[4 6] transition state (TS) and competing stepwise diradical (6 2) cycloaddition; both dimers subsequently undergo intramolecular [4 2] cycloadditions afford thermally stable tetracyclic products. TS the 10π-electron version prototype bispericyclic cyclopentadiene discovered Caramella et al. in 2002. Quantum mechanical studies using several common DFT functionals...

We consider the ground state of a harmonically trapped Bose-Einstein condensate within Gross-Pitaevskii theory including effective-range corrections for two-body zero-range potential. The resulting nonlinear Schr\"odinger equation is solved analytically in Thomas-Fermi approximation neglecting kinetic-energy term. present results chemical potential and profiles, discuss boundary conditions, compare to usual approach. several ways increase influence experiment with magnetically tunable...

An enantioselective organocatalytic strategy, combining Brønsted base and N-heterocyclic carbene catalysis in a unique manner, is demonstrated for concise construction of the privileged cyclopenta[<italic>b</italic>]benzofuran scaffold, present many bioactive compounds having both academic commercial interests.

We demonstrate the possibility of existence meta-stable N-body Efimov states in trapped Bose systems with large scattering length. calculate spectra N=3,4,5,6, and 7 bosons using a stochastic variational method restricted correlated Gaussian basis. For each system calculations reveal series where energy r.m.s. radius exhibit characteristic exponential dependence upon state number. also estimate contribution these to recombination rate Bose-Einstein condensates.

We consider a system of three identical bosons near Feshbach resonance in the universal regime with large scattering length usually described by model-independent zero-range potentials. employ adiabatic hyperspherical approximation and derive rigorous large-distance equation for potential finite-range interactions. The effective range correction to must be supplemented new term same order. nonadiabatic can decisive. Efimov physics is always confined between length. analytical results agree...

The Diels-Alder reactions of tropolone and its conjugate base with N-methylmaleimide have been explored computationally experimentally. Previous studies the [4+2] cycloaddition under basic conditions show that both endo- exo-products are obtained in similar, but variable amounts. Density functional theory (ωB97X-D) explorations potential energy surfaces, molecular dynamics trajectories reaction involves an ambimodal transition state for ammonium tropolonate N-methylmaleimide, similar amounts...

We calculate the energy and condensate fraction of a system trapped bosons interacting via short-range two-body potential with positive scattering length. The is attractive has bound state. When length small compared to trap model independent: all models —attractive, repulsive zero-range— provide similar results. large differs qualitatively from zero-range models. In this regime becomes independent length, both converging towards finite constants.

Abstract A novel enantioselective (8+3) cycloaddition between donor–acceptor cyclopropanes and heptafulvenoids catalysed by a chiral bifunctional Brønsted base is described. Importantly, the reaction, which leverages an anionic activation strategy, divergent from prototypical Lewis‐acid protocols. series of cyclopropylketones react with tropones affording desired cycloadducts in high yield enantiomeric excess. For barbiturate substituted heptafulvenes, proceeds good yield, excellent...

Abstract The Diels–Alder reactions of tropolone and its conjugate base with N‐methylmaleimide have been explored computationally experimentally. Previous studies the [4+2] cycloaddition under basic conditions show that both endo‐ exo‐products are obtained in similar, but variable amounts. Density functional theory (ωB97X‐D) explorations potential energy surfaces, molecular dynamics trajectories reaction involves an ambimodal transition state for ammonium tropolonate N‐methylmaleimide,...

We calculate energies, condensate fractions and two‐body correlation functions for a system of N identical bosons in trap. Both attractive repulsive finite‐range interactions with large range positive scattering lengths are used. At small the is model independent. When length comparable to trap properties depend on details interaction.