193819-07-7Relevant articles and documents
83. Chiral 2-Aryl-2-methyl-2H-1-benzopyrans: Synthesis, Characterization of Enantiomers, and Barriers to Thermal Racemization
Harie, Guenaelle,Samat, Andre,Guglielmetti, Robert,Van Parys, Inge,Saeyens, Wim,De Keukeleire, Denis,Lorenz, Klaus,Mannschreck, Albrecht
, p. 1122 - 1132 (1997)
The ease of thermal breaking of the C(sp3)-O bond of the 2-aryl-2-methyl-2H-1-benzopyrans 1-9 was evaluated by measuring the free energy (ΔG≠e) of the racemization reaction of optically active compounds. The variation ot Δ
Pd-Catalyzed Formal [3 + 3] Heteroannulation of Allylic gem-Diacetates: Synthesis of Chromene-Based Natural Products and Exploration of Photochromic Properties
Kumar, Prashant,Kumar, Pravesh,Venkataramani, Sugumar,Ramasastry
, p. 963 - 970 (2022/01/19)
Palladium-catalyzed allylic alkylation reactions of allylic gem-diacetates are rarely explored. This work unveils an unusual chemical reactivity pattern of allylic gem-diacetates and establishes them as new prototypes to synthesize complex benzo[f]chromene systems. Under the reaction conditions, the diacetates behave as 1,3-dicationic equivalents and undergo a [3 + 3] heteroannulation with 2-naphthols (and meta-substituted phenols) to produce novel polycyclic chromenes possessing spiro-, tri-, and tetrasubstituted carbon centers. The versatility of the method is demonstrated in the synthesis of several chromene-based bioactive natural products. Further, interesting photochromic properties of the new classes of benzo[f]chromenes are also discovered.
Ligand-controlled regiodivergent π-allyl palladium catalysis enables a switch between [3+2] and [3+3] cycloadditions
Xia, Yu,Bao, Qiao-Fei,Li, Yuke,Wang, Li-Jing,Zhang, Bo-Sheng,Liu, Hong-Chao,Liang, Yong-Min
supporting information, p. 4675 - 4678 (2019/05/02)
Reported herein is the use of ligands to tune the regioselectivity and reactivity of palladium-catalyzed [3+2] and [3+3] cycloadditions. Diverse synthesis with vinylethylene carbonates (VECs) as well as free naphthols has been explored to construct four different valuable polycyclic frameworks in a broad substrate scope.
Catalysis by β-Cyclodextrin Hydrate - Synthesis of 2,2-Disubstituted 2H-Chromenes in Aqueous Medium
Ghatak, Avishek,Khan, Sagar,Bhar, Sanjay
supporting information, p. 435 - 443 (2016/02/18)
A cost-effective, operationally simple and eco-compatible protocol for the one-pot synthesis of photochromic pyrans by the reaction of propargyl alcohols as well as propargyl ethers with differently substituted phenols under ambient atmosphere in aqueous
Synthesis and Photochromic Behaviour of Naphthopyrans, Pyranoquinolines, Pyranoquinazolines and Pyranoquinoxalines
Pozzo, Jean-Luc,Samat, Andre,Guglielmetti, Robert,Dubest, Roger,Aubard, Jean
, p. 725 - 738 (2007/10/03)
New chromenes annulated with different six-membered azaheterocycles were prepared, i.e., the 3H-pyrano[3,2-f]quinolines 9/10 and 14, the 8H-pyrano[2,3-h]isoquinoline 11, the 8H-pyrano[3,2-f]quinazoline 12, the 8H-pyrano[3,2-f]quinoxaline 13, and the 2H-pyrano[2,3-f]isoquinoline 15. The synthesis was achieved using conveniently substituted α,β-unsaturated aldehydes and organotitanium intermediates arising from azaheterocyclic phenols. Their photochromic behaviour (photocolouration yield, UV/VIS spectrum of photomerocyanines, rate constant of thermal bleaching) were studied besides those of corresponding naphthopyrans. The heterocycle effect and the role of substituents in the pyran moiety were investigated quantitatively through the study of the photochromic properties and the solvent effects. Diaryl-substituted azino-fused chromenes, especially isoquinoline derivatives, exhibit increased colourabilities and bathochromically shifted spectra for photomerocyanines which open up new prospects for photochromic applications.
