77036-87-4Relevant articles and documents
Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C-H Activation
Di Monaco, Sabrina,Pang, Benjamin Piaoxiang,Rahman, Md. Shafiqur,Thai, Anh Ngoc,Wang, Chang-Sheng,Wang, Chen,Yoshikai, Naohiko
supporting information, p. 12878 - 12889 (2020/08/21)
A catalytic system comprising a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines and related azines, imidazo[1,2-a]pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic systems for analogous transformations, the present catalytic systems not only feature convenient setup using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp) but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Meanwhile, the present catalytic system proved to promote exclusively C5-selective alkenylation of imidazo[1,2-a]pyridine derivatives. Mechanistic studies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkenyl(carbamoyl)cobalt intermediate.
GAS/SOLID-REACTIONS WITH SULFUR COMPOUNDS
Kaupp, Gerd,Luebben, Doris,Sauerland, Olaf
, p. 109 - 120 (2007/10/02)
The various types of gas/solid-reactions (addition, elimination, substitution, condensation, catalyzed cycloaddition) in different branches of sulfur chemistry (heterocycles, S-vinyl-compounds, thioethers, thiols, sulfur dioxide) are reviewed, new types a
-Eliminations and -Substitutions of a Bicyclic β-Lactone Dithioacetal
Kaupp, Gerd
, p. 4271 - 4275 (2007/10/02)
Photolytic, thermal, and acid-catalyzed -eliminations of methanethiol from the benzobicyclic β-lactone dithioaqcetal 1 to form the benzothiazole derivatives 4 and 5 are investigated.Competing reactions are -substitutions, which ultimately yield 2-benzylbenzothiazole (6) and benzaldehyde.Intermediate 7 is isolated upon careful hydrolysis.These reactions are compared to -eliminations from the 1,5-benzothiazepine 9 and to its -rearrangement to give 10. 9 and 10 are not intermediates in the reactions of 1.The stereochemistry of 7 and 10 is discussed.
