92439-00-4Relevant academic research and scientific papers
Iridium-Catalyzed Cycloisomerization of Alkynoic Acids: Synthesis of Unsaturated Lactones
Huang, Yi,Zhang, Xianghe,Dong, Xiu-Qin,Zhang, Xumu
supporting information, p. 782 - 788 (2020/01/08)
The iridium-catalyzed cycloisomerization of various alkynoic acids was successfully developed, and a series of five-, six-, and especially seven-membered unsaturated lactones were constructed with moderate yields and excellent regioselectivities (up to 68
Rhodium(I)-Catalyzed Decarbonylative Aerobic Oxidation of Cyclic α-Diketones: A Regioselective Single Carbon Extrusion Strategy
Golime, Gangadhararao,Kim, Hun Young,Oh, Kyungsoo
, p. 942 - 945 (2018/02/22)
A rhodium-catalyzed decarbonylative aerobic oxidation of cyclic α-diketones has been developed for the first time, where the regioselective formations of α-pyrones and isocoumarins have been achieved. The current decarbonylative aerobic oxidation pathway proceeds via the C-C bond cleavage followed by a C-O bond formation, representing a biomimetic oxidation approach to unsaturated six-membered cyclic lactones. The unique ability of rhodium catalysts to induce the decarbonylative aerobic oxidation opens up a new synthetic toolbox that utilizes the "regioselective single carbon" extrusion strategy.
Selective oxymetalation of terminal alkynes via 6-endo cyclization: mechanistic investigation and application to the efficient synthesis of 4-substituted isocoumarins
Kita, Yuji,Yata, Tetsuji,Nishimoto, Yoshihiro,Chiba, Kouji,Yasuda, Makoto
, p. 6041 - 6052 (2018/08/01)
The cyclization of heteroatom-containing alkynes with π acidic metal salts is an attractive method to prepare heterocycles because the starting materials are readily available and the organometallic compounds are useful synthetic intermediates. A new organometallic species in the heterocyclization provides an opportunity to synthesize heterocycles that are difficult to obtain. Herein, we describe a novel cyclic oxymetalation of 2-alkynylbenzoate with indium or gallium salts that proceeds with an unusual regioselectivity to give isocoumarins bearing a carbon-metal bond at the 4-position. This new type of metalated isocoumarin provided 3-unsubstituted isocoumarins that have seldom been investigated despite their important pharmacological properties. Indium and gallium salts showed high performance in the selective 6-endo cyclization of terminal alkynes while boron or other metals such as Al, Au, and Ag caused 5-exo cyclization or decomposition of terminal alkynes, respectively. The metalated isocoumarin and its reaction intermediate were unambiguously identified by X-ray crystallographic analysis. The theoretical calculation of potential energy profiles showed that oxyindation could proceed via 6-endo cyclization under thermodynamic control while previously reported oxyboration would give a 5-membered ring under kinetic control. The investigation of electrostatic potential maps suggested that the differences in the atomic characters of indium, boron and their ligands would contribute to such a regioselective switch. The metalated isocoumarins were applied to organic synthetic reactions. The halogenation of metalated isocoumarins proceeded to afford 4-halogenated isocoumarins bearing various functional groups. The palladium-catalyzed cross coupling of organometallic species with organic halides gave various 4-substituted isocoumarins. A formal total synthesis of oosponol, which exhibits strong antifungal activity, was accomplished.
External oxidant-free dehydrogenative lactonization of 2-arylbenzoic acids via visible-light photocatalysis
Shao, Ailong,Zhan, Jirui,Li, Na,Chiang, Chien-Wei,Lei, Aiwen
, p. 3582 - 3589 (2018/04/14)
An external oxidant-free C-H functionalization/C-O bond formation reaction for constructing benzo-3,4-coumarins accompanied by quantitative H2 evolution has been developed. High functional group tolerance and excellent reaction efficiency are s
One-Pot Sequential N-Heterocyclic Carbene/Rhodium(III) Catalysis: Synthesis of Fused Polycyclic Isocoumarins
Youn, So Won,Yoo, Huen Ji
supporting information, p. 2176 - 2183 (2017/07/07)
A one-pot sequential N-heterocyclic carbene–rhodium (NHC-Rh) catalysis is described, demonstrating the compatibility of NHC and Rh catalysts. N-Heterocyclic carbene-catalyzed aerobic oxidation of benzaldehydes and subsequent rhodium(III)-catalyzed oxidative coupling/annulation with multiple bonds enabled the formation of two C–O bonds and one C–C bond in a single pot. This operationally easy, one-pot protocol under air provides access to a diverse array of valuable fused polycyclic isocoumarins. (Figure presented.).
Synthesis of 4-arylisocoumarins (=4-aryl-1H-2-benzopyran-1-ones) through acidic hydrolysis of (Z)-2-(1-aryl-2-methoxyethenyl)benzaldehydes, followed by oxidation
Kobayashi, Kazuhiro,Miyatani, Wataru,Kuroda, Minami
, p. 2173 - 2178 (2014/01/06)
4-Arylisocoumarins (=4-aryl-1H-2-benzopyran-1-ones) 6 were prepared from 2-(1-aryl-2-methoxyethenyl)-1-bromobenzenes 1. Successive treatment of these bromo styrenes with BuLi and 1-formylpiperidine gave a mixture of (E)- and (Z)-2-(1-aryl-2-methoxyethenyl)benzaldehydes 2. Hydrolysis of (Z)-isomers with conc. HBr, followed by pyridinium chlorochromate (PCC) oxidation of the resulting 1H-2-benzopyran-1-ol derivatives 4 (and 5), afforded the desired products. Copyright
Highly selective palladium-catalyzed direct c-h α-monoarylation of carbonyl compounds using water containing the surfactant polyoxyethylene- α-tocopheryl sebacate (PTS) as a solvent
Lessi, Marco,Masini, Tiziana,Nucara, Luca,Bellina, Fabio,Rossi, Renzo
experimental part, p. 501 - 507 (2011/04/15)
Highly selective direct C-H α-monoarylation reactions of 4-chromanones, ketones and 2-phenylacetaldehyde with aryl halides have been performed in satisfactory yields by using a tris(dibenzylideneacetone) dipalladium(0)/tri-tert-butylphosphine tetrafluoroborate catalyst system, potassium bicarbonate as the base and a solvent consisting of pure water containing a small amount of polyoxyethylene-α-tocopheryl sebacate (PTS). Analogous reaction conditions have been employed in a tandem process leading to phenyl-substituted isocoumarins from carbonyl compounds and methyl 2-bromobenzoate.
Synthesis of isocoumarins and α-pyrones via palladium-catalyzed annulation of internal alkynes
Larock, Richard C.,Doty, Mark J.,Han, Xiaojun
, p. 8770 - 8779 (2007/10/03)
A number of 3,4-disubstituted isocoumarins and polysubstituted α- pyrones have been prepared in good yields by treating halogen- or triflate- containing aromatic and α,β-unsaturated esters, respectively, with internal alkynes in the presence of a palladiu
REACTIONS OF 2-ACYLBENZOATES WITH DIMETHYLOXOSULPHONIUM METHYLIDE: A NOVEL ROUTE TO ISOCOUMARINS
Beautement, Kevin,Clough, John M.
, p. 3025 - 3028 (2007/10/02)
Treatment of 2-benzoylbenzoates with dimethyloxosulphonium methylide (1) gives 4-phenylisocoumarins (2); methyl 2-acetylbenzoate gives 4-methylene-3,4-dihydroisocoumarin (3) under the same conditions.
