[reaction: see text] Stable oxapalladacycles have been prepared and converted into a series of highly functionalized 2H-1-benzopyrans via regioselective insertion of activated alkynes.
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http://dx.doi.org/10.1021/ol0201456 | DOI Listing |
Org Biomol Chem
October 2022
Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, India.
A new BF·OEt-catalyzed approach was developed for the construction of 2,2'-spirobi-2-1-benzopyrancarboxylates by reacting ethyl 2-(chloromethyl)-2-hydroxy-2-chromene-3-carboxylates with salicylaldehydes. The reactions proceeded through the formation of C-C and C-O bonds in one pot. Structure assignment of compound 3c was confirmed by single crystal X-ray analysis.
View Article and Find Full Text PDFMolecules
May 2019
Department of Organic Chemistry and Pharmacognosy, Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1 J. Bouchier buld., 1164 Sofia, Bulgaria.
Coumarins are an important class of natural heterocyclic compounds that have attracted considerable synthetic and pharmacological interest due to their various biological activities. This review emphasizes on the synthetic methods for the preparation of dialkyl 2-oxo-2-1-benzo- pyran-3-phosphonates and alkyl 1,2-benzoxaphosphorin-3-carboxylates. Their chemical properties as acceptors in conjugate addition reactions, [2+2] and [3+2] cycloaddition reactions are discussed.
View Article and Find Full Text PDFAcc Chem Res
January 2016
Research and Development Initiative, Chuo University, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.
Organic synthesis based on straightforward transformations is essential for environmentally benign manufacturing for the invention of novel pharmaceuticals, agrochemicals, and organoelectronic materials in order to ultimately realize a sustainable society. Metal-catalyzed C-H bond-cleaving functionalization has become a promising method for achieving the above goal. For site-selective C-H bond cleavage, so-called directing groups, i.
View Article and Find Full Text PDFEur J Med Chem
June 2014
Laboratoire de Pharmacodynamie et de Thérapeutique, Université Libre de Bruxelles, Faculté de Médecine, 808 Route de Lennik, B-1070 Bruxelles, Belgium.
The present study described the synthesis of original R/S-6-alkylsulfonylamino-3,4-dihydro-2,2-dimethyl-2H-1-benzopyrans bearing a 3- or 4-substituted phenylthiourea or phenylurea moiety at the 4-position. Their biological effects were evaluated both on insulin-secreting and smooth muscle cells and were compared to those of reference KATP channel activators such as (±)-cromakalim, diazoxide and previously synthesized cromakalim analogues. The study aimed at exploring the influence of the introduction of an alkylsulfonylamino substituent at the 6-position of 2,2-dimethylchromans in order to improve biological activity, tissue selectivity but also hydrophilicity of dihydrobenzopyran derivatives.
View Article and Find Full Text PDFJ Org Chem
December 2013
Department of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal.
A novel methodology has been developed to obtain enantiopure 2-C-glycosyl-3-nitrochromenes. First, (Z)-1-bromo-1-nitroalkenes were prepared from the corresponding sugar aldehydes through a sodium iodide-catalyzed Henry reaction with bromonitromethane followed by elimination of the resulting 1-bromo-1-nitroalkan-2-ols. In the next step, reaction of the sugar-derived (Z)-1-bromo-1-nitroalkenes with o-hydroxybenzaldehydes afforded enantiopure (2S,3S,4S)-3-bromo-3,4-dihydro-4-hydroxy-3-nitro-2H-1-benzopyrans, which, upon SmI2-promoted β-elimination, yielded chiral enantiopure 2-C-glycosyl-3-nitrochromenes.
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