Ru(II)-Catalyzed β-Carboline Directed C–H Arylation and Isolation of Its Cycloruthenated Intermediates
摘要:
A Ru(II)-catalyzed C-H arylation approach has been developed utilizing beta-carboline alkaloids as the directing group. Selective formations of diarylated products from moderate to excellent yields were accomplished. Broad substrate scope with excellent functional group tolerance for C1-phenyl/thienyl/PAHs-beta-carbolines was demonstrated. X-ray crystal structure of cycloruthenated complex 2cr and no arylation reaction with model substrate 13 strongly suggests that N2 is the directing group than N9 in C1-aryl-beta-carbolines. Catalytic properties and stability of the cycloruthenated complexes have been explored. Library of biologically relevant new,beta-carboline derivatives and isolation of its cycloruthenated intermediates are the highlights of this work
Employing TBN/TEMPO as the catalysts and oxygen as the oxidant, the biologically and pharmaceutically significant tetrahydro-β-carboline and β-carboline alkaloid scaffolds that used to be obtained by multi-step processes can now be selectively obtained in only one-step via direct aerobicoxidative Pictet–Spengler reactions of tryptamines with alcoholsundermildconditions, with water generated as
catalytic processes. In this work, a H3PO4·12WO3/OMS-2 nanocomposite catalyst ([PW]-OMS-2) was prepared through the oxidation of a Mn(II) salt with sodium phosphotungstate by KMnO4. Comprehensive characterization indicates that different Mn2+ precursors significantly affected the crystalline phase and morphology of the as-synthesized catalysts and only MnSO4·H2O as the precursor could lead to a cryptomelane
A rapid, microwave-assisted synthesis of beta-carbolines via a Successive condensation/cyclization/dehydrogenation approach is described. This methodology involves the coupling of various tryptamines with aromatic aldehydes/glyoxals. The product imine undergoes a Pictet-Spengler cyclization followed by a final dehydrogenation to yield beta-carbolines in a three-step domino reaction. The use of the bifunctional catalyst Pd/C/K-10 combined with microwave irradiation enabled the synthesis of beta-carbolines in short reaction times and in good to excellent yields. (C) 2009 Elsevier Ltd. All rights reserved.