Copper-catalyzed Pummerer type reaction of α -thio aryl/heteroarylacetates: Synthesis of aryl/heteroaryl α -keto esters
作者:Pipas Saha、Sumit Kumar Ray、Vinod K. Singh
DOI:10.1016/j.tetlet.2017.03.069
日期:2017.5
A copper catalyzed Pummerer type reaction of α-thio aryl/heteroarylacetates is described for the first time. This transformation represents a new route to synthesize α-keto esters, which are important intermediates for pharmaceuticals and organic synthesis. The reaction proceeds via in situ generation of a thionium ion that undergoes hydrolysis to furnish α-keto esters in synthetically viable yields
Fe(OTf)2 was used to catalyze the insertionreaction of α-diazocarbonyls into S–H bonds at 40 °C. A wide range of α-thioesters were obtained in yields up to 96% within 24–48 h from their corresponding α-diazoesters. A variety of thiols were used for the unprecedented insertionreaction with an α-diazoketone, leading to yields up to 85% of α-thioketones.
Room Temperature Coupling of Aryldiazoacetates with Boronic Acids Enhanced by Blue Light Irradiation
作者:Amanda F. Silva、Marco A. S. Afonso、Rodrigo A. Cormanich、Igor D. Jurberg
DOI:10.1002/chem.201905812
日期:2020.5.4
visible-light-promoted photochemical protocol is reported for the coupling of aryldiazoacetates with boronic acids. This photochemicalreaction shows great enhancement compared to the same protocol performed in the absence of light. Except for a few cases, the room temperature coupling in the dark (thermal process) generally does not work. When it does, it is likely to also involve free carbenes as key intermediates
Blue light-promoted N–H insertion of amides, isatins, sulfonamides and imides into aryldiazoacetates: Synthesis of unnatural α-aryl amino acid derivatives
作者:Celso Y. Okada、Caio Y. dos Santos、Igor D. Jurberg
DOI:10.1016/j.tet.2020.131316
日期:2020.12
A photochemical protocol using blue light allows the N–H insertion of amides, isatins, sulfonamides and imides into aryldiazoacetates to afford the corresponding α-amino esters. This method is experimentally simple, inexpensive and tolerates numerous functional groups, thus allowing the straightforward preparation of a variety of α-aryl amino acid derivatives in good yields.
Photoinduced Proton‐Transfer Reactions for Mild O‐H Functionalization of Unreactive Alcohols
作者:Sripati Jana、Zhen Yang、Fang Li、Claire Empel、Junming Ho、Rene M. Koenigs
DOI:10.1002/anie.201915161
日期:2020.3.27
hexafluoroisopropanol and the diazoalkane acts as an unreactive hydrogen‐bonding complex. Only after photoexcitation does this complex undergo a protonation‐substitution reaction to the reaction product. Investigations on the applicability of this photochemical transformation show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of