An unprecedented example of a chiral phosphoric acid-catalyzed atroposelective Pictet-Spengler reaction of N-arylindoles is reported. Highly enantioenriched N-aryl-tetrahydro-β-carbolines with C-N bond axial chirality are obtained via dynamic kinetic resolution. The hydrogen bond donor introduced on the bottom aromatic ring, forming a secondary interaction with the phosphoryl oxygen, is essential to achieving high enantioselectivity. A wide variety of substituents are tolerable with this transformation to provide up to 98 % ee. The application of electron-withdrawing group-substituted benzaldehydes enables the control of both axial and point stereogenicity. Biological evaluation of this new and unique scaffold shows promising antiproliferative activity and emphasizes the significance of atroposelective synthesis.
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http://dx.doi.org/10.1002/anie.202100363 | DOI Listing |
Molecules
December 2024
Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Material Science, Hebei University, Baoding 071002, China.
An efficient and convenient strategy has been successfully developed for the preparation of novel hydroxylated alkaloid derivatives (also called fused multicyclic iminosugars) from -toluenesulfonylated sugars through a Pictet-Spengler-type mechanism. This method is highly stereoselective, does not require metal catalysts, and capable of conducting gram level reactions (with a 53% yield). Some of such iminosugars had an intermediate antiproliferative effect on HCT116 tumor cells.
View Article and Find Full Text PDFChem Asian J
December 2024
Organic and Bio-Organic Chemistry laboratory, CSIR-Central Leather Research Institute (CSIR-CLRI), Chennai, 600020, India.
The efficient pentaflurophenol-catalyzed Pictet-Spengler cyclization was carried out which led to the formation of spirobenzazepinoindole. This article examines the methods and modifications of Pictet-Spengler cyclization in the synthesis of intricate organic compounds, emphasizing its significance in drug discovery and development. This reaction generally entails the condensation of an amine with an aldehyde or ketone, succeeded by an intramolecular cyclization step catalyzed by pentafluorophenol, an alternate for metal-mediated catalysts due to its facile characteristics which render it an invaluable asset in organic synthesis and catalysis.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, United States.
Functionalizing graphene with exact pore size, specific functional groups, and precision doping poses many significant challenges. Current methods lack precision and produce random pore sizes, sites of attachment, and amounts of dopant, leading to compromised structural integrity and affecting graphene's applications. In this work, we report a strategy for the synthesis of functionalized graphitic materials with modifiable nanometer-sized pores via a Pictet-Spengler polymerization reaction.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
Hubei Research Center of Fundamental Science-Chemistry, Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
Chiral tetrahydro-β-carbolines, as one of the most intriguing subtypes of indole alkaloids, have emerged as the privileged units in plenty of natural products and biologically active molecules with an impressive range of bioactive properties. However, the stereodivergent construction of these valuable skeletons containing multistereogenic centers from readily available starting materials remains very challenging, especially, in view of the introduction of an axial chirality. Herein, we developed an efficient method toward enantioenriched tetrahydro-β-carbolines with readily available tryptophan-derived aldimine esters and allylic carbonates under mild reaction conditions.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Department of Chemistry, Birla Institute of Technology & Science, Pilani, Pilani, 333 031 (Rajasthan, India.
Due to its structural complexity and intrinsic sensitivity of bridged aminal junction, 2,6-diazabicyclo[2.2.2]octane (2,6-DABCO) has remained a highly desirable target in synthetic chemistry.
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