An alcohol-directed, nickel-catalyzed three-component umpolung carboamination of unactivated alkenes with aryl/alkenylboronic esters and electrophilic aminating reagents is reported. This transformation is enabled by specifically tailored O-(2,6-dimethoxybenzoyl)­hydroxylamine electrophiles that suppress competitive processes, including undesired β-hydride elimination and transesterification between the alcohol substrate and electrophile. The reaction delivers the desired 1,2-carboaminated products with generally high regio- and syn-diastereoselectivity and exhibits a broad scope of coupling partners and alkenes, including complex natural products. Various mechanistic experiments and analysis of the stereochemical outcome with a cyclic alkene substrate, as confirmed by X-ray crystallographic analysis, support alcohol-directed syn-insertion of an organonickel­(I) species.

Methoxide abstraction from gold acetylide complexes of the form (L)Au[η -C≡CC(OMe)ArAr'] (L=IPr, P( Bu) (ortho-biphenyl); Ar/Ar'=C H X where X=H, Cl, Me, OMe) with trimethylsilyl trifluoromethanesulfonate (TMSOTf) at -78 °C resulted in the formation of the corresponding cationic gold diarylallenylidene complexes [(L)Au=C=C=CArAr'] OTf in ≥85±5 % yield according to H NMR analysis. C NMR and IR spectroscopic analysis of these complexes established the arene-dependent delocalization of positive charge on both the C1 and C3 allenylidene carbon atoms. The diphenylallenylidene complex [(IPr)Au=C=C=CPh ] OTf reacted with heteroatom nucleophiles at the allenylidene C1 and/or C3 carbon atom.

Diarylation of alkenyl sulfonamides with aryl iodides and aryl boronic esters under nickel catalysis is reported. The developed method tolerates coupling partners with disparate electronic properties and substitution patterns. 1,2-and 1,1-Disubstituted alkenes, as well as alkenes distal from the directing group, are all accommodated. Control experiments are consistent with a N-Ni coordination mode of the directing group, which stands in contrast to earlier reports on amide-directed 1,2-diarylation that involve carbonyl coordination. The synthetic utility of the method arises from the dual function of the sulfonamide as both a directing group and masked amine nucleophile. This is highlighted by various product diversifications where complex amine compounds are synthesized in a two-step sequence of N-functionalization and deprotection of the sulfonyl group. File list (4) download file view on ChemRxiv Manuscript.pdf (632.65 KiB) download file view on ChemRxiv Supporting Info.pdf (21.57 MiB) download file view on ChemRxiv 2a.cif (407.62 KiB) download file view on ChemRxiv 2ab.cif (0.98 MiB)

Cycloaddition of an isotopically labeled 7-phenyl-1,6-enyne catalyzed by a mixture of LAuCl [L = P­(t-Bu)2 o-biphenyl)] and AgSbF6 forms the corresponding 6-phenylbicyclo[3.2.0]­hept-6-ene with concomitant scrambling of the olefinic CPh (C6) and CH (C7) groups of the product. The extent of C6/C7 scrambling was sensitive to the nature of the silver salt and was likewise observed in the cycloaddition of the 7-phenyl-1,6-enyne catalyzed by mixtures of [LAuNCMe]+SbF6 – and Brønsted acids such as HOTf. These observations and low-temperature NMR analysis of organic and organometallic intermediates in the cycloaddition process were in accord with a mechanism for C6/C7 scrambling initiated by protonation of free bicyclo[3.2.0]­hept-7-ene to generate a bicyclo[3.2.0]­heptyl cation that undergoes reversible alkyl migration, presumably involving bicyclo[4.1.0]- and bicyclo[3.1.1]­heptyl cations prior to elimination of the C7 proton.

Cyclic­(alkyl)­(amino)­carbene (CAAC) ligands are found to perturb regioselectivity of the copper-catalyzed carboboration of terminal alkynes, favoring the less commonly observed internal alkenylboron regiosomer through an α-selective borylcupration step. A variety of carbon electrophiles participate in the reaction, including allyl alcohol derivatives and alkyl halides. The method provides a straightforward and selective route to versatile trisubstituted alkenylboron compounds that are otherwise challenging to access.

A flurry of recent research has centered on harnessing the power of nickel catalysis in organic synthesis. These efforts have been bolstered by contemporaneous development of well‐defined nickel (pre)catalysts with diverse structure and reactivity. In this report, we present ten different bench‐stable, 18‐electron, formally zero‐valent nickel–olefin complexes that are competent pre‐catalysts in various reactions. Our investigation includes preparations of novel, bench‐stable Ni(COD)(L) complexes (COD=1,5‐cyclooctadiene), in which L=quinone, cyclopentadienone, thiophene‐S‐oxide, and fulvene. Characterization by NMR, IR, single‐crystal X‐ray diffraction, cyclic voltammetry, thermogravimetric analysis, and natural bond orbital analysis sheds light on the structure, bonding, and properties of these complexes. Applications in an assortment of nickel‐catalyzed reactions underscore the complementary nature of the different pre‐catalysts within this toolkit.

This paper presents a mixture item response tree (IRTree) model for extreme response style. Unlike traditional applications of single IRTree models, a mixture approach provides a way of representing the mixture of respondents following different underlying response processes (between individuals), as well as the uncertainty present at the individual level (within an individual). Simulation analyses reveal the potential of the mixture approach in identifying subgroups of respondents exhibiting response behavior reflective of different underlying response processes. Application to real data from the Students Like Learning Mathematics (SLM) scale of Trends in International Mathematics and Science Study (TIMSS) 2015 demonstrates the superior comparative fit of the mixture representation, as well as the consequences of applying the mixture on the estimation of content and response style traits. We argue that methodology applied to investigate response styles should attend to the inherent uncertainty of response style influence due to the likely influence of both response styles and the content trait on the selection of extreme response categories.

Highly reactive cationic gold vinyl carbene/allylic cation complexes are generated in solution via γ-ionization of gold vinyl complexes.