106584-13-8Relevant articles and documents
Rhodium-Catalyzed ortho-Selective Carbene C-H Insertion of Unprotected Phenols Directed by a Transient Oxonium Ylide Intermediate
Guo, Rui-Ting,Zhang, Ya-Lin,Tian, Jun-Jie,Zhu, Ke-Yu,Wang, Xiao-Chen
, p. 908 - 913 (2020)
ortho-Selective carbene C-H insertion of unprotected phenols is achieved with dimethyl diazomalonate under the catalysis of [Rh(COD)Cl]2. After the C-H insertion, subsequent cyclization and electrophilic addition of another carbene molecule affords tris-carboxylate-substituted 2-benzofuranones as the final reaction products. The enantioselective variant has been developed with the use of chiral diene ligands. Mechanistic experiments indicate that a transient oxonium ylide directing group might be responsible for the regiocontrol at the C-H activation step.
Synthesis of biaryls via intramolecular free radical ipso-substitution reactions
Ujjainwalla, Feroze,Da Mata, Maria Lucília E.N.,Pennell, Andrew M.K.,Escolano, Carmen,Motherwell, William B.,Vázquez, Santiago
, p. 6701 - 6719 (2015/08/24)
A variety of functionalised biaryls and heterobiaryls are prepared by intramolecular free radical [1,5]-ipso-substitution using sulfonamide and sulfonate derived tethering chains. The overall efficiency of the process is determined by appropriately positioned substituents on the aromatic acceptor ring. The extension of the process to benzylic sulfonates and their corresponding N-methylsulfonamide alternatives as substrates in potential [1,6]-ipso-substitution reactions leads mainly to the alternative [1,7] addition products.
Dioxygenase-catalysed oxidation of monosubstituted thiophenes: sulfoxidation versus dihydrodiol formation.
Boyd, Derek R,Sharma, Narain D,Gunaratne, Nimal,Haughey, Simon A,Kennedy, Martina A,Malone, John F,Allen, Christopher C,Dalton, Howard
, p. 984 - 994 (2007/10/03)
Toluene dioxygenase (TDO)-catalysed sulfoxidation, using Pseudomonas putida UV4, was observed for the thiophene substrates 1A-1N. The unstable thiophene oxide metabolites, 6A-6G, 6K-6N, spontaneously dimerised yielding the corresponding racemic disulfoxide cycloadducts 7A-7G, 7K-7N. Dimeric or crossed [4 + 2] cycloaddition products, derived from the thiophene oxide intermediates 6A and 6D or 6B and 6D, were found when mixtures of thiophene substrates 1A and 1D or 1B and 1D were biotransformed. The thiophene sulfoxide metabolite 6B was also trapped as cycloadducts 17 or 18 using stable dienophiles. Preferential dioxygenase-catalysed oxidation of the substituent on the thiophene ring, including exocyclic sulfoxidation (1H-1J) and cis-dihydroxylation of a phenyl substituent (1G and 1N), was also observed. An enzyme-catalysed deoxygenation of a sulfoxide in P. putida UV4 was noticed when racemic disulfoxide cyclo-adducts 7A, 7B and 7K were converted to the corresponding enantioenriched monosulfoxides 8A, 8B and 8K via a kinetic resolution process. The parent thiophene 1A and the 3-substituted thiophenes 1K-1N were also found to undergo ring dihydroxylation yielding the cis/trans-dihydrodiol metabolites 9A and 9K-9N. Evidence is provided for a dehydrogenase-catalysed desaturation of a heterocyclic dihydrodiol (9Kcis/9Ktrans) to yield the corresponding 2,3-dihydroxythiophene (24) as its preferred thiolactone tautomer (23). A simple model to allow prediction of the structure of metabolites, formed from TDO-catalysed bacterial oxidation of thiophene substrates 1, is presented.