Despite the widespread application of hypervalent iodines, the corresponding λ -bromanes are less explored. Herein we report a general, safe, and high-yielding strategy to access cyclic diaryl λ -bromanes. These unique compounds feature reactivity that is appealing and complementary to that of λ -iodanes, generating arynes under mild reaction conditions and in the presence of a weak base. Accordingly, formal meta-selective transition-metal-free C-O and C-N couplings may be achieved. Mechanistic studies unambiguously support the aryne generation mechanism.
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http://dx.doi.org/10.1002/anie.202103625 | DOI Listing |
Angew Chem Int Ed Engl
November 2024
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
The synthesis of chiral 1,1-diaryl compounds, particularly those containing a pyridine moiety, is of significant interest due to their pharmaceutical applications. Here, we report the development of a copper-catalyzed enantioselective 1,4-hydropyridylation of conjugated dienes. Utilizing 2-fluoropyridine as the electrophile, CuOAc, and the chiral ligand Tol-BINAP, we optimized reaction conditions to achieve the desired chiral 1,1-diaryl products containing both a pyridine and a cis-crotyl group.
View Article and Find Full Text PDFChem Asian J
November 2024
Department of Chemistry, Faculty of Science, Niigata University, Nishi-ku, Niigata, 950-2181, Japan.
Despite the significant development and extensive application of phthalocyanine and related azaporphyrins, little attention has been paid to meso-N-substituted azaporphyrinoids. Here, we report new derivatives of 5,10,20-triaryl-5,15-diazaporphyrinoids (ArDAP), which are reversibly redox-switchable between the 18π- and 19π-electron state. Four kinds of metal(II) complexes and free bases of ArDAP were prepared by metal-templated cyclization of metal(II) complexes of 5,10,15-triaryl-10-azabiladiene-ac with sodium azide or copper-catalyzed N-phenylation of 10,20-diaryl-5,15-diazaporphyrins (ArDAP) with diphenyliodonium hexafluorophosphate.
View Article and Find Full Text PDFCurr Top Med Chem
October 2024
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ataturk University, Erzurum, Turkey.
Cancer is a multifaceted disease with high mortality rates, and current treatments face challenges such as chemoresistance and tumor adaptation. Since Virchow reported the first case of cancer-related chronic inflammation, numerous clinical and epidemiological studies have indicated that around 15-20% of malignant tumors are caused by inflammation. Cyclooxygenase-2 (COX-2), which is the key enzyme in inflammation, has been implicated in tumorigenesis through various mechanisms, including promoting angiogenesis, inhibiting apoptosis, and enhancing the invasiveness of cancer cells.
View Article and Find Full Text PDFWhile hypervalent halogens are versatile reagents enabling diverse reactions in organic synthesis, the utility of hypervalent chlorine compounds, particularly cyclic λ-chloranes, remains underdeveloped despite their unique electronic properties and innate enhanced reactivity. Herein, we illustrate the elusive ligand coupling reaction of cyclic λ-chloranes that suppresses the more facile competing reaction modality involving benzyne intermediates. The methodology can be performed in three-component as well as two-component fashions, offering direct access to a wide range of unsymmetrically substituted biaryl molecules in very high yields and excellent -regioselectivity.
View Article and Find Full Text PDFOrg Biomol Chem
October 2024
Department of Chemistry, Tunghai University, No. 1727, Sec. 4, Taiwan Boulevard, Xitun District, Taichung 407224, Taiwan.
A series of unsymmetrical 2,4-disubstituted pyranocoumarins and 3-bromo-2-(4-bromoalkoxy)-derived pyranocoumarins were synthesized the palladium-catalyzed C-H arylation of 4-phenyl-4,5-pyrano[3,2-]chromen-5-ones with aryl iodide and the three-component reaction of 4-phenyl-4,5-pyrano[3,2-]chromen-5-one with bromine and cyclic ether, respectively.
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