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We report a two-step one-pot synthesis of the 2,6-diarylmorpholin-3-one core based on the Ugi reaction of 2-oxoaldehyde with 2-hydroxycarboxylic acid, a primary amine and tert -butyl isocyanide followed by a triflic acid-promoted intramolecular condensation accompanied by the loss of the isocyanide-originated amide moiety. The overall transformation proceeds with complete retention of stereoconfiguration at the 2-hydroxycarboxylic acid-derived chiral center, allowing the target morpholin-3-ones to be obtained in an enantiopure form. Subsequent double bond hydrogenation and amide reduction allow the degree of unsaturation to be reduced, providing a convenient entry to the cis -2,6-diphenylmorpholine motif.

We report highly enantioselective synthesis of L-α-hydroxy carboxylic acids (L-αHCAs) via enzymatic intramolecular Cannizzaro reaction of (hetero)aryl glyoxals in the presence of glutathione-independent human glyoxalase DJ-1. Combined with the optimized synthesis of D-αHCAs using glyoxalases I and II, this approach offers a general, scalable and operationally simple access to both enantiomers of α-hydroxy acids in moderate to excellent yields with uniformly high enantioselectivity.

A chemoselective strategy toward a variety of fused heterocyclic scaffolds relying on a three-component condensation of heterocyclic ketene aminals (HKAs) or corresponding thioaminals with aryl glyoxals and cyclic 1,3-dicarbonyl compounds has been developed and explored. Depending on the applied combination of substrates, the strategy can be tuned to provide straightforward access to imidazo[1,2- a ]quinoline, pyrrolo[1,2- a ]imidazole, and pyrrolo[2,1- b ]thiazole frameworks.

We study the coherent excitation of the ^{2}S_{1/2}→^{2}F_{7/2} electric octupole (E3) transition by twisted light modes with a single ^{171}Yb^{+} ion in the dark center of a vortex beam. The intensity distribution of the beam is mapped as a function of the ion's position by measuring the light shift on an auxiliary electric quadrupole transition. In the center of the vortex beam, we observe excitation of the E3 transition with a fivefold reduced light shift in comparison to excitation by plane wave radiation for the same Rabi frequency. We measure the excitation probabilities for Laguerre-Gaussian twisted light modes of first and second order for different polarization patterns at various orientations of the ion quantization axis with respect to the beam propagation vector. We compare the experimental results with theoretical predictions and find good qualitative agreement.

Starting from a screening hit, a set of analogs was synthesized based on a 4-(2-aminoethyl)piperidine core not associated previously with trace amine-associated receptor 1 (TAAR1) modulation in the literature. Several structure-activity relationship generalizations have been drawn from the observed data, some of which were corroborated by molecular modeling against the crystal structure of TAAR1. The four most active compounds (EC 50 for TAAR1 agonistic activity ranging from 0.033 to 0.112 μM) were nominated for evaluation in vivo. The dopamine transporter knockout (DAT-KO) rat model of dopamine-dependent hyperlocomotion was used to evaluate compounds' efficacy in vivo. Out of four compounds, only one compound (AP163) displayed a statistically significant and dose-dependent reduction in hyperlocomotion in DAT-KO rats. As such, compound AP163 represents a viable lead for further preclinical characterization as a potential novel treatment option for disorders associated with increased dopaminergic function, such as schizophrenia.

A straightforward route to a large and diverse library of trisubstituted imidazoles was established via a three-component reaction of 2-oxoaldehydes, 1,3-dicarbonyl compounds, and acyclic nitrogen bis-nucleophiles. The obtained products were subsequently explored in a photochemical cyclization yielding a variety of imidazole-fused polycyclic compounds.

We report a measurement of the radiative lifetime of the ^{2}F_{7/2} level of ^{171}Yb^{+} that is coupled to the ^{2}S_{1/2} ground state via an electric octupole transition. The radiative lifetime is determined to be 4.98(25)×10^{7}  s, corresponding to 1.58(8) yr. The result reduces the relative uncertainty in this exceptionally long excited state lifetime by 1 order of magnitude with respect to previous experimental estimates. Our method is based on the coherent excitation of the corresponding transition and avoids limitations through competing decay processes. The explicit dependence on the laser intensity is eliminated by simultaneously measuring the resonant Rabi frequency and the induced quadratic Stark shift. Combining the result with information on the dynamic differential polarizability permits a calculation of the transition matrix element to infer the radiative lifetime.

In this report, we introduce a new strategy for controlling the stereochemistry in Ugi adducts. Instead of controlling stereochemistry directly during the Ugi reaction we have attempted to stereodefine the chiral center at the peptidyl position through the post-Ugi functionalization. In order to achieve this, we chose to study 2-oxo-aldehyde-derived Ugi adducts many of which partially or fully exist in the enol form that lacks the aforementioned chiral center. This in turn led to their increased nucleophilicity as compared to the standard Ugi adducts. As such, the stereocenter at the peptidyl position could be installed and stereodefined through the reaction with a suitable electrophile. Towards this end, we were able to deploy an asymmetric cinchona alkaloid-promoted electrophilic fluorination producing enantioenriched post-Ugi adducts fluorinated at the peptidyl position., (Copyright © 2020, Wang et al.; licensee Beilstein-Institut.)

A three-component reaction of an azulene, an aryl glyoxal and a 1,3-dicarbonyl compound has been elaborated to access a series of azulene derivatives. Some of these azulene-containing adducts were further subjected to post-MCR transformations to assemble azulene-heterocycle conjugates., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This focused review aims to summarize recent developments in the processes involving additions of secondary propargylamines to various heteroallenes and subsequent transition metal-catalyzed or electrophile-mediated cyclizations. The utility of this convenient and tunable strategy spans from the carbon dioxide fixation and target-oriented synthesis of complex natural and biologically active products to the generation of extended synthetic libraries of diverse oxygen-, nitrogen- and sulfur-containing heterocycles. For comparative purposes, the analogous transformations of propargylic alcohols are also highlighted in this account.

This study analyzes the radiation produced by a point charge intersecting the interface between a vacuum and a chiral isotropic medium. We deduce analytical expressions for the Fourier components of an electromagnetic field in both vacuum and medium for arbitrary charge velocity. The main focus is on investigating the far field in a vacuum. The distinguishing feature of the interface with a chiral isotropic medium is that the field in the vacuum area contains both copolarization (coinciding with the polarization of the self-field of a charge) and cross-polarization (orthogonal to the polarization of the self-field). Using a saddle-point approach, we obtain asymptotic representations for the field components in the far-field zone for typical frequency ranges of the Condon model of the chiral medium. We note that a so-called lateral wave is generated in a vacuum for certain parameters. The main contribution to the radiation at large distances is presented by two (co- and cross-) spherical waves of transition radiation. These waves are coherent and result in a total spherical wave with elliptical polarization, with the polarization coefficient being determined by the chirality of the medium. We present typical radiation patterns and ellipses of polarization.

A novel procedure for the Heck-Suzuki tandem reaction suitable for the construction of nitrogen-containing medium rings was developed to provide access toward the 3-benzazepine framework.

A three-component reaction of a 2-aminoazine, a 2-oxoaldehyde, and a cyclic 1,3-dicarbonyl compound providing access toward a novel class of imidazo[1,2-a]azine derivatives was developed and studied. The scope of the process was thoroughly explored under three different reaction conditions resulting in the generation of a small library of title compounds and highlighting the possibility of case-specific approach.

Cationic gold-catalyzed cycloisomerizations of propargylureas, derived in situ from secondary propargylamines and aryl or alkyl isocyanates, have been studied. The reaction outcome was found to be different from what was previously observed for the tosyl isocyanate-derived ureas in terms of both regio- and chemoselectivity. As a result, the current protocol offers efficient access to the 3,4-dihydropyrimidin-2(1H)-one core through the 6-endo-dig N-cyclization.

We analyze the electromagnetic field generated by a point charge moving with a constant velocity in an isotropic chiral medium. We work in the frame of the Condon dispersion model for the weak chirality and ultrarelativistic motion of the charge. We show that the field of a moving charge contains two low-frequency wave processes with right- and left-hand circular polarizations and a high-frequency wave process with a right-hand polarization. The low-frequency wave field exists at an arbitrary charge velocity and oscillates at a frequency of the order of the resonant frequency of the medium. This effect is of most importance near the charge trajectory. The high-frequency wave field arises at an ultrahigh velocity and is essential near the plane of charge dislocation for a sufficiently large offset from the trajectory. This wave field oscillates at a frequency that is considerably greater (up to several orders) than the resonant frequency of the medium. Intriguingly, both of these phenomena exist in the domain in front of the charge, thus producing the low- and high-frequency wave forerunners correspondingly.