622-76-4Relevant articles and documents
Elucidation of reaction process through β-halogen elimination in CuCN-mediated cyanation of (E)-1-bromo-2-iodoalkene
Endo, Naoki,Kanaura, Mao,Iwasawa, Tetsuo
, p. 483 - 486 (2016)
The previously unknown reaction process involved with metal-mediated β-halogen elimination is described, including a description of a vinylic Rosenmund-von Braun reaction of (E)-(1-bromo-2-iodobut-1-en-1-yl)benzene. We investigated the product structures on the basis of crystallographic analyses and revealed that copper cyanide would form bifurcated paths to deliver the isomeric mixtures.
Migratory Aptitudes in Rearrangements of Destabilized Vinyl Cations
Brewer, Matthias,Cleary, Sarah E.,Hensinger, Magenta J.,Hong, Xin,Qin, Zhi-Xin
, p. 15154 - 15164 (2019)
The Lewis acid-promoted generation of destabilized vinyl cations from β-hydroxy diazo ketones leads to an energetically favorable 1,2-shift across the alkene followed by an irreversible C-H insertion to give cyclopentenone products. This reaction sequence overcomes typical challenges of counter-ion trapping and rearrangement reversibility of vinyl cations and has been used to study the migratory aptitudes of nonequivalent substituents in an uncommon C(sp2) to C(sp) vinyl cation rearrangement. The migratory aptitude trends were consistent with those observed in other cationic rearrangements; the substituent that can best stabilize a cation more readily migrates. However, density functional theory calculations show that the situation is more complex. Selectivity in the formation of one conformational isomer of the vinyl cation and facial selective migration across the alkene due to an electrostatic interaction between the vinyl cation and the adjacent carbonyl oxygen work in concert to determine which group migrates. This study provides valuable insight into predicting migration preferences when applying this methodology to the synthesis of structurally complex cyclopentenones that are differentially substituted at the α and β positions.
Binuclear Pd(I)-Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
Zhang, Yang,Torker, Sebastian,Sigrist, Michel,Bregovi?, Nikola,Dydio, Pawe?
supporting information, p. 18251 - 18265 (2020/11/02)
Since its discovery in 1938, hydroformylation has been thoroughly investigated and broadly applied in industry (>107 metric ton yearly). However, the ability to precisely control its regioselectivity with well-established Rh- or Co-catalysts has thus far proven elusive, thereby limiting access to many synthetically valuable aldehydes. Pd-catalysts represent an appealing alternative, yet their use remains sparse due to undesired side-processes. Here, we report a highly selective and exceptionally active catalyst system that is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader context, the new mechanistic understanding enables the development of other carbonylation reactions of high importance to chemical industry.
Palladium-catalyzed methylation of terminal alkynes
Wang, Wei-Feng,Wu, Xiao-Feng
, (2019/10/22)
In this communication, a palladium-catalyzed procedure for the methylation of terminal alkynes has been developed. With N,N,N-trimethylbenzenaminium trifluoromethanesulfonate as the methyl source, various desired products were obtained in moderate to good yields. Both aromatic and aliphatic alkynes are applicable.
