83922-79-6Relevant articles and documents
Allene C(sp2)-H Activation and Alkenylation Catalyzed by Palladium
Aouane, Fran?oise A.,Baik, Mu-Hyun,Carreira, Erick M.,Schreib, Benedikt S.,Son, Mina
supporting information, p. 21705 - 21712 (2022/01/03)
The selective transition-metal-mediated activation of C(sp2)-H bonds of allenes is a formidable challenge because of the competitive, intrinsic reactivity of cumulated double bonds. Herein, we report a Pd-catalyzed C-H alkenylation of electronically unbiased allenes, affording penta-1,2,4-triene products in up to 94% yield. A picolinamide directing group enables the formation of putative allenyl-palladacycles, which subsequently participate in a turnover-limiting Heck-type reaction with electron-deficient alkene coupling partners. This mechanistic proposal is consistent with experimental and computational investigations. Additionally, we report for the first time the use of picolinamide N,O-acetals as readily removable auxiliaries for C-H activation reactions, allowing the efficient alkenylation of allenyl carbinol derivatives. Successful removal of the directing groups without affecting the reactive penta-1,2,4-triene substructure of the products is demonstrated.
1,2-Hydrogen migration and alkene formation in the photoexcited states of alkylphenyldiazomethanes
?elebi, Sol,Leyva, Soccoro,Modarelli, David A.,Platz, Matthew S.
, p. 8613 - 8620 (2007/10/02)
Laser flash photolysis of alkylphenyldiazomethanes in the presence of pyridine produces easily detected ylides. The data indicate that photolysis of alkylphenyldiazomethanes leads to both carbene formation and direct formation of rearrangement products which do not derive from relaxed carbene intermediates.
Formation and Reactivity of ?-Radical Cation Intermediates in the C-C Coupling Reaction of Phenyldiazomethanes by One-Electron Oxidation
Ishiguro, Katsuya,Ikeda, Masatoshi,Sawaki, Yasuhiko
, p. 3057 - 3066 (2007/10/02)
One-electron oxidation of phenyldiazomethanes afforded cis-stilbene predominantly.The reaction was independent of the oxidation methods, e.g., electrolysis, copper(II), triarylaminium salts, or photosensitized one-electron oxidtions.The C-C coupling reaction was retarded by introducing α-substituents on phenyldiazomethanes.The ESR spectra of diazoalkane radical cations could be obtained during the electrolysis at low temperature and the resulting spectra revealed their unique electronic structure as ?-radicals for most cases.When a bulky tert-butyl group was substituted, the corresponding ?-radical cation was observed, but the C-C coupling reaction did not occur.The novel HOMO-LUMO switching by one-electron removal from the HOMO ?-orbital of diazomethane is explained by the interaction of phenyl group with the C-N-N ?-radical moiety.The C-C coupling reaction proceeds via facile cycloaddition between the diazomethane and ?-radical cation, and the preferential formation of cis-olefins is based on the secondary orbital interaction between the two phenyl groups.The structure and the stability of radical cation intermediates are rationalized on the basis of ab initio calculations.
CYCLOADDITIONS OF DISUBSTITUTED DIAZO COMPOUNDS TO P-CHLORO(BISTRIMETHYLSILYL) METHYLENE PHOSPHINE.
Thoraval, J. Y.,Nagai, W.,Yeung Lam Ko, Y. Y. C.,Carrie, R.
, p. 3859 - 3868 (2007/10/02)
Disubstituted diazo compounds rapidly add to P-chloro (bistrimethylsilyl) methylene phosphine at low temperature. 1H, 31P and 13C NMR allow the characterization of the resulting cycloadducts and the establisment of the stereochemistry of the resulting cycloadducts which are potential precursors of ?3λ5 bis methylene phosphorane by nitrogen extrusion.
