153496-81-2Relevant academic research and scientific papers
Formal Carbene Insertion into C?O or C?N Bond: An Efficient Strategy for the Synthesis of 2-Substituted 2H-Chromene Derivatives from Chromene Acetals or Hemiaminal Ethers
Zhang, Dan,Hu, Wenhao
supporting information, p. 2446 - 2452 (2018/05/14)
We report the palladium/Br?nsted acid co-catalyzed formal insertion of carbene into the C?O or C?N bond of 2H-chromene acetals or hemiaminal ethers. This transformation was initiated by the Br?nsted acid-promoted cleavage of the C?O or C?N bond, followed by modification of the leaving alcohol or amino fragments with palladium carbenes, and reassembly of the modified fragments. A variety of C-2 functionalized 2H-chromene derivatives were obtained in moderate yield (43～75%) with good to excellent diastereoselectivities (up to >95:5 dr) under mild conditions. (Figure presented.).
Ring-closing metathesis of allylic O,O- and N,O-acetals
Kinderman, Sape S.,Doodeman, Robin,Van Beijma, Jetze W.,Russcher, Jaap C.,Tjen, Kim C. M. F.,Kooistra, T. Martijn,Mohaselzadeh, Homayun,Van Maarseveen, Jan H.,Hiemstra, Henk,Schoemaker, Hans E.,Rutjes, Floris P. J. T.
, p. 736 - 748 (2007/10/03)
A variety of allylic O,O- and N,O-acetals were synthesized using a mild palladium-catalyzed coupling of an alcohol or sulfonamide with an alkyl or aryl 1,2-propadienyl ether. The resulting linear acetals were used for the synthesis of unsaturated rings via ring-closing metathesis, in which the acetal carbon-a precursor for oxycarbenium or N-sulfonyliminium ions, respectively-served as a reactive center for further introduction of functional groups. The products-unsaturated oxygen and nitrogen heterocyclic scaffolds - offer multiple opportunities for derivatization as illustrated with the synthesis of substituted dihydropyrans, chromenes, enantiopure tetrahydropyridines and an enantiomerically pure quinolizidine amino acid.
Synthesis of 2-substituted chromenes via ring-closing metathesis and stable 1-benzopyrylium ions
Doodeman, Robin,Rutjes, Floris P. J. T.,Hiemstra, Henk
, p. 5979 - 5983 (2007/10/03)
2-Substituted chromenes were obtained via combination of ring-closing metathesis of allylic acetals to the corresponding cyclic acetals, followed by Lewis acid-mediated functionalization of the resulting stable 1- benzopyrylium ion with suitable nucleophiles. (C) 2000 Elsevier Science Ltd.
Chiral Chromenes: Synthesis, Separation of Enantiomers and Barriers to Racemization
Loncar, Linda,Otocan, Klaudio,Mintas, Mladen,Troetsch, Thomas,Mannschreck
, p. 209 - 216 (2007/10/02)
2H-Chomenes 3 and 4 have been synthesized by reduction of the appropriate lactone with diisobutylaluminium hydride and subsequent O-alkylation of the resulting lactols.Separations or enrichments of enantiomers were achieved by liquid chromatography on tri
