Angewandte Chemie International Edition

Zhao, Fengqian; Ai, Han‐Jun; Wu, Xiao‐Feng

doi: 10.1002/anie.202200062pmid: 35175679

Controllable production of α‐keto amides and amides from the same substrates is an attractive goal in the field of transition‐metal‐catalyzed (double‐)carbonylation. Herein, a novel copper‐catalyzed highly selective double carbonylation of alkyl bromides has been developed. Moderate to good yields of α‐keto amides were obtained as the only products. In the case of alkyl iodides, double‐ and mono‐carbonylation can be achieved controllably under different conditions.

Baek, Yunjung; Betley, Theodore A.

doi: 10.1002/anie.202115437pmid: 35172039

The reactivity of (TrL)Co (TrL=5‐mesityl‐1,9‐(trityl)dipyrrin) toward various aryl azides was examined to elucidate the electronic structure and reactivity of dipyrrinato cobalt aryl nitrenoid complexes. Herein, we demonstrate the synthesis of a CoII diketimide complex [(TrL)Co(NC6F5)]2 and its reversible C−C bond cleavage to yield a monomeric Co nitrenoid complex (TrL)Co(NC6F5). Exposure of [(TrL)Co(NC6F5)]2 to an excess amount of an H‐atom donor cleanly affords the CoII anilide complex (TrL)Co(NHC6F5). The half‐order decay of [(TrL)Co(NC6F5)]2 via H‐atom abstraction (HAA) reveals saturation kinetic behavior indicating a pre‐equilibrium between [(TrL)Co(NC6F5)]2 and (TrL)Co(NC6F5) prior to HAA. Furthermore, (TrL)Co(NC6F5) undergoes reductive coupling with another equivalent of azide to furnish the four‐coordinate tetrazido complex (TrL)Co(κ2‐N4(C6F5)2), expulsion of a fluorine atom to afford (TrL)CoF, and N‐group transfer reactivity to PPh3.

Ma, Jiguo; Gao, Bin; Song, Guanshui; Zhang, Ruixin; Wang, Qingfang; Ye, Zi; Chen, Wen‐Wen; Zhao, Baoguo

doi: 10.1002/anie.202200850pmid: 35182094

Owing to the strong nucleophilicity of the NH2 group, free‐NH2 glycinates react with MBH acetates to usually deliver N‐allylated products even in the absence of catalysts. Without protection of the NH2 group, chiral pyridoxal catalysts bearing an amide side chain at the C3 position of the naphthyl ring switched the chemoselectivity of the glycinates from intrinsic N‐allylation to α‐C allylation. The reaction formed chiral multisubstituted glutamic acid esters as SN2′–SN2′ products in good yields with excellent stereoselectivity (up to 86 % yield, >20 : 1 dr, 97 % ee). As compared to pyridoxal catalysts bearing an amide side arm at the C2 position, the pyridoxals in this study have a bigger catalytic cavity to enable effective activation of larger electrophiles, such as MBH acetates and related intermediates. The reaction is proposed to proceed via a cooperative bifunctional catalysis pathway, which accounts for the high level of diastereo‐ and enantiocontrol of the pyridoxal catalysts.

Hempelmann, Jan; Müller, Peter C.; Ertural, Christina; Dronskowski, Richard

doi: 10.1002/anie.202204053pmid: N/A

Tiessen, Natalia; Keßler, Mira; Neumann, Beate; Stammler, Hans‐Georg; Hoge, Berthold

doi: 10.1002/anie.202281761pmid: N/A

Chen, Ke‐Wei; Chen, Zhi‐Han; Yang, Shuang; Wu, Shu‐Fang; Zhang, Yu‐Chen; Shi, Feng

doi: 10.1002/anie.202116829pmid: 35080808

The first highly atroposelective construction of N−N axially chiral indole scaffolds was established via a new strategy of de novo ring formation. This strategy makes use of the organocatalytic asymmetric Paal–Knorr reaction of well‐designed N‐aminoindoles with 1,4‐diketones, thus affording N‐pyrrolylindoles in high yields and with excellent atroposelectivities (up to 98 % yield, 96 % ee). In addition, this strategy is applicable for the atroposelective synthesis of N−N axially chiral bispyrroles (up to 98 % yield, 97 % ee). More importantly, such N−N axially chiral heterocycles can be converted into chiral organocatalysts with applications in asymmetric catalysis, and some molecules display potent anticancer activity. This work not only provides a new strategy for the atroposelective synthesis of N−N axially chiral molecules but also offers new members of the N−N atropisomer family with promising applications in synthetic and medicinal chemistry.

Li, Lianggui; Shan, Chunhui; Shi, Jiarong; Li, Wensheng; Lan, Yu; Li, Yang

doi: 10.1002/anie.202117351pmid: 35170157

The stannum–ene reactions of both benzyne and cyclohexyne were realized, which is particularly suitable for cyclohexyne with a broad substrate scope and excellent chemoselectivity. Our DFT calculations via distortion/interaction analysis revealed that both stannum– and hydrogen–ene reactions with cyclohexyne have later transition states due to their higher distortion energies in the transition states than those in benzyne reactions, which lead to enhanced Pauli repulsion as the decisive factor in the interaction energy accompanied with enlarged energy gap between two types of ene reactions. Therefore, excellent chemoselectivity was disclosed in the cyclohexyne–ene reaction.

Helmers, Ingo; Hossain, Muhammad Saddam; Bäumer, Nils; Wesarg, Paul; Soberats, Bartolome; Shimizu, Linda S.; Fernández, Gustavo

doi: 10.1002/anie.202200390pmid: 35112463

Herein, we present a strategy to enable a maintained emissive behavior in the self‐assembled state by enforcing an anti‐cooperative self‐assembly involving weak intermolecular dye interactions. To achieve this goal, we designed a conformationally flexible monomer unit 1 with a central 1,3‐substituted (diphenyl)urea hydrogen bonding synthon that is tethered to two BODIPY dyes featuring sterically bulky trialkoxybenzene substituents at the meso‐position. The competition between attractive forces (H‐bonding and aromatic interactions) and destabilizing effects (steric and competing conformational effects) limits the assembly, halting the supramolecular growth at the stage of small oligomers. Given the presence of weak dye–dye interactions, the emission properties of molecularly dissolved 1 are negligibly affected upon aggregation. Our findings contribute to broadening the scope of emissive supramolecular assemblies and controlled supramolecular polymerization.

Yang, Jiacai; Yao, Heliang; Guo, Yuedong; Yang, Bowen; Shi, Jianlin

doi: 10.1002/anie.202200480pmid: 35143118

Fenton reactions have been recently applied in tumor catalytic therapy, whose efficacy suffers from the unsatisfactory reaction kinetics of Fe3+ to Fe2+ conversion. Here we introduce a co‐catalytic concept in tumor catalytic therapy by using a two‐dimensional molybdenum disulfide (MoS2) nanosheet atomically dispersed with Fe species. The single‐atom Fe species act as active sites for triggering Fenton reactions, while the abundant sulfur vacancies generated on the nanosheet favor electron capture by hydrogen peroxide for promoting hydroxyl radical production. Moreover, the 2D MoS2 support also acts as a co‐catalyst to accelerate the conversion of Fe3+ to Fe2+ by the oxidation of active Mo4+ sites to Mo6+, thereby promoting the whole catalytic process. The 2D nanocatalyst exhibits a desirable catalytic performance, as well as a significantly enhanced anticancer efficacy both in vitro and in vivo, which indicates the feasibility for applying such a co‐catalytic concept in tumor therapy.

Fritz, Patrick W.; Chen, Tianyang; Ashirov, Timur; Nguyen, Anh‐Dao; Dincă, Mircea; Coskun, Ali

doi: 10.1002/anie.202116527pmid: 35172031

Tetraoxa[8]circulenes (TOCs) are a class of hetero[8]circulenes featuring a planar cyclooctatetraene core with a mixed aromatic/antiaromatic motif that governs their electronic properties. Polymeric TOCs (pTOCs) have been the subject of several computational simulations because they are predicted to be low‐band‐gap semiconductors, but they have not been available synthetically yet. Here, we report the first example of pTOCs, a new family of porous semiconductors, synthesized under ionothermal conditions through the intermolecular cyclization of 1,4,5,8‐anthracene tetrone. pTOCs are porous, with surface areas up to 1656 m2 g−1, and exhibit light‐switchable and tunable semiconducting properties.