28773-73-1Relevant academic research and scientific papers
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.
UNE SYNTHESE ORIGINALE ET INATTENDUE D'ISOCOUMARINES FONCTIONNELLES
Babin, P.,Dunogues, J.
, p. 4389 - 4392 (2007/10/02)
Reaction of Ph3P=CH-COOEt with ortho benzoyl benzoic acid derivates offers an easy and surprising entry to functional isocoumarins via the thermal decomposition of the keto-ylide intermediates or by subsequent oxidation of the expected indenones.
