Homochiral and heterochiral cis-bis-cycloplatinated-[6]helicene derivatives 1b(1,2), as representative examples of platina[6]helicenes that share a common platinum center, have been prepared. A diastereo- and enantioselective synthesis, which combines CH activation and dynamic isomerization from heterochiral structure 1b(2) into homochiral structure 1b(1), is also described. Overall, this isomerization process results in the transfer of chiral information from one helicene moiety to the other one. The chiroptical properties of homochiral (P)- and (M)-1b(1) were greatly modified upon oxidation into their corresponding (P)- and (M)-diiodo-Pt(IV) complexes (5). The changes were also analyzed by performing theoretical calculations. C-H activation in the synthesis of organometallic helicenes is further demonstrated by the preparation of cis-bis-cycloplatinated-[8]helicene 1c.
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http://dx.doi.org/10.1002/chem.201302479 | DOI Listing |
Org Lett
January 2025
State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China.
Highly asymmetric (3+3) annulation of diaziridines with oxiranes via C-N bond cleavage in diaziridine was achieved under 10 mol % of chiral copper(II) complex as the catalyst under mild reaction conditions. With Cu(OTf) as the Lewis acid and C-symmetric imidazolidine-pyrroloimidazolone pyridine as the ligand, diverse tetrahydro-[1,3,4]-oxadiazines were obtained by stereospecific C-N/C-O bond formation in moderate to good yields (up to 93% yield) and high diastereo- (>20:1 dr) and enantioselectivities (up to 92% ee). The catalytic cycle and stereochemical model were proposed by DFT calculation.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen 518132, China.
The absolute and relative configurations of bioactive chiral molecules are typically relevant to their biological properties. It is thus highly important and desirable to construct all possible stereoisomers of a lead candidate or a given bioactive natural compound. Synergistic dual catalysis has been recognized as a reliable synthetic strategy for a variety of predictable stereodivergent transformations.
View Article and Find Full Text PDFOrg Lett
January 2025
School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China.
The catalytic asymmetric multicomponent acylation/rearrangement/cyclization of alkenylfurans with acyl oxime esters/arylamines or acyl oxime esters/arylamines/hydroxylamine has been developed. This method employs synergistic photoredox/Brønsted acid catalysis, enabling the efficient and versatile synthesis of multifunctionalized [3.2.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Direct synthesis of enantioenriched scaffolds with multiple adjacent stereocenters remains an important yet challenging task. Herein, we describe a highly diastereo- and enantioselective Cu-catalyzed alkylboration of cyclopropenes, with less reactive alkyl iodides as electrophiles, for the efficient synthesis of -substituted borylated cyclopropanes bearing three consecutive stereocenters. This protocol features mild conditions, a broad substrate scope, and good functional group tolerance, affording an array of chiral borylated cyclopropanes in good to high yields with excellent diastereo- and enantioselectivities.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China.
Enantioselective hydrogenation of tetrasubstituted alkenes to form 1,2-contiguous stereocenters is a particularly appealing but highly challenging transformation in asymmetric catalysis. Despite the notable progress achieved in enantioselective hydrogenation over the past decades, enantioselective hydrogenation of all-carbon tetrasubstituted alkenes containing multiple alkyl groups remains an unsolved challenge. Here, we report a rhodium-catalyzed highly diastereo- and enantioselective hydrogenation of diverse acyclic multisubstituted alkenes under mild conditions.
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