1403327-75-2Relevant academic research and scientific papers
Sp3-sp2 vs sp3-sp3 C-C site selectivity in Rh-catalyzed ring opening of benzocyclobutenol: A DFT study
Ding, Lina,Ishida, Naoki,Murakami, Masahiro,Morokuma, Keiji
, p. 169 - 178 (2014/01/23)
The Csp3-Csp2 vs Csp3-Csp3 site selectivity in the C-C bond activation in Rh-catalyzed ring opening of benzocyclobutenol was systematically investigated using density functional theory (DFT). The catalytic cycle includes three elementary steps: the proton transfer from the substrate to a rhodium hydroxide, the C-C cleavage, and the proton transfer from water onto a carbon forming the final product with regeneration of the rhodium hydroxide. The site selectivity is determined by the C-C cleavage step; the Csp3-Csp2 cleavage is favored over the Csp3-Csp3 cleavage because the former transition state is stabilized by an interaction between the benzene ring of the substrate and Rh. DMSO, a more polar solvent, reduces the site selectivity as the more polar Csp3-Csp3 transition state (TS) is stabilized more than the Csp3-Csp2 TS and decreases the advantage of the latter TS. DPPF ligand is bulky, and the steric repulsion on the tighter Csp3-Csp2 TS causes the loss of the site selectivity. For the even more crowded Rh(P(t-Bu)3)2 catalyst, one phosphine has to dissociate before the C-C cleavage reaction takes place, and the advantage of the Csp3-Csp2 TS is regained for the less crowded RhP(t-Bu)3 active catalyst.
Rhodium-catalyzed ring opening of benzocyclobutenols with site-selectivity complementary to thermal ring opening
Ishida, Naoki,Sawano, Shota,Masuda, Yusuke,Murakami, Masahiro
supporting information, p. 17502 - 17504,3 (2020/09/16)
A rhodium catalyst induced ring opening of benzocyclobutenols with selective cleavage of the C(sp2)-C(sp3) bond adjacent to the hydroxyl group. The site-selectivity markedly contrasted with that of their thermal ring-opening reaction. The rhodium-catalyzed ring opening led to the development of a new alkyne insertion reaction constructing a dihydronaphthalene framework.
