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Demonstrated herein is a keteniminium triggered dienone‐phenol rearrangement of yne‐dienone and a regioselective intramolecular 6‐endo‐dig cyclization of aryl‐propargyl ether cascade for the synthesis of 2H‐chromene bearing ketene‐N,O‐acetals. The gold‐catalyst and ynamide combination forms a keteniminium species in situ and makes the dienone‐phenol rearrangement viable with 1,2‐migration of common alkyl substituents (methyl and ethyl) and phenyl group. The transformation tolerates common functional groups and N‐sulfonyl protecting groups in ynamides exhibiting broad scope. The transformation proceeds through intramolecular proton transfer to the vinylic gold species; deuterium scrambling study supports this observation. [ABSTRACT FROM AUTHOR]

The concept of dual catalysis is an emerging area holding high potential in terms of preparative efficiency, yet faces severe challenges in compatibility of reaction conditions and interference of catalysts. The transition‐metal catalyzed stereoselective hydrogenation of olefins and ketones typically proceeds under different reaction conditions and/or uses a different reductant. As a result, these two types of hydrogenations can normally not be performed in the same pot. Herein, the stereocontrolled hydrogenation of enones to saturated alcohols is described, enabled by orthogonal dual iridium catalysis, using molecular hydrogen for both reductions. In this one‐pot procedure, N,P‐iridium catalysts (hydrogenation active towards olefins) and NHC,P‐iridium catalysts (hydrogenation active towards ketones) operated independently of one another allowing the construction of two contiguous stereogenic centers up to 99 % ee, 99/1 d.r. Ultimately, by simple selection of the chirality of either ligands, the enone could be efficiently reduced to all four stereoisomers of the saturated alcohol in equally high stereopurity. This degree of stereocontrol for the synthesis of different stereoisomers by dual transition‐metal catalyzed hydrogenation was previously not attained. The generality in substituted enones (alkyl, aryl, heteroaryl) demonstrate the wide applicability of this concept. [ABSTRACT FROM AUTHOR]

Silver-catalyzed cyclization and cycloisomerization of ketene N,N-acetals at room temperature has been developed to access a variety of highly substituted cyclobutene-fused azepine and 1,2-dihydropyridine derivatives. This cost-effective method is reliably implemented for the gram-scale synthesis of azepine and dihydropyridine derivatives. The iodo group in the periphery of the dihydropyridine motif can be functionalized with both Suzuki and Sonogashira reactions. [ABSTRACT FROM AUTHOR]

Benzo-fused nitrogen heterocycles are common features of bioactive molecules, and the enantioselective synthesis of their substituted analogues is an important goal. In this paper we demonstrate a practical and mechanistically intriguing approach to the enantioselective synthesis of 1-arylbenzazepines and their analogues. The reaction sequence starts with an asymmetric migratory ring expansion of indoline, tetrahydroquinoline, or tetrahydrobenzazepine ureas on treatment with a chiral lithium amide base. Treatment of the ring-expanded ureas with acid triggers a two-atom ring contraction-an 'azatropic shift' in which one urea nitrogen displaces the other-with almost complete retention of stereochemistry. Aminolysis of the urea products provides enantioenriched 1-aryl-tetrahydrobenzazepine derivatives and their congeners, including an analogue of an intermediate in the synthesis of the drug solifenacin. Deuteration, in situ IR, and DFT studies provide evidence for the mechanisms of the reaction steps., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A practical, transition metal-free method allows the enantioselective synthesis of α,α-diarylmethylamines by asymmetric α-arylation of benzylamines. Enantioselective lithiation of N'-aryl-N-benzyl-N-isopropyl ureas using a chiral lithium amide base generates a benzyllithium that undergoes an unactivated stereospecific intramolecular nucleophilic aromatic substitution to generate an α,α-diarylmethylamine in the form of its urea derivative, in up to >99 % ee. Treatment with acid induces an "azatropic shift" with retention of configuration, the product of which may be hydrolysed to the target amine., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A three-component Pd-catalyzed coupling of ynamides, aryl diazonium salts, and aryl boronic acids for the synthesis of novel triaryl-substituted enamides is described. This transformation represents the first example of an umpolung regioselective unsymmetrical syn-1,2-diarylation/aryl-olefination of ynamides. The aryl moieties of the diazonium salt (electrophile) and boronic acid (nucleophile) are explicitly incorporated in the electrophilic α- and nucleophilic β-position, respectively, of the ynamide, resulting in a single isomer of the N-bearing tetrasubstituted olefin. The scope is broad (68 examples), showing excellent functional-group tolerance. DFT calculations substantiate the rationale of the mechanistic cycle and the regioselectivity. The chemoselectivity and synthetic potential of the enamide products were also studied., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A regioselective sulfonyl/sulfinyl migration cycloisomerization cascade of alkyne-tethered ynamides is developed in the presence of XPhosgold catalyst. This reaction is the first example of a general [1,3]-sulfonyl migration from the nitrogen center to the β-carbon atom of ynamides, followed by umpolung 5-endo-dig cyclization of the ynamide α-carbon atom to the gold-activated alkyne, and final deaurative [1,5]-sulfinylation. This process allows the synthesis of peripherally decorated unconventional 4-sulfinylated pyrroles with broad scope from N-propargyl-tethered ynamides. In contrast, N-homopropargyl-tethered ynamides undergo intramolecular tetradehydro Diels-Alder reaction to provide 2,3-dihydro-benzo[f]indole derivatives. Control experiments and density-functional theory studies were used to study the reaction pathways., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)