Oxygen Acidity of Ring Methoxylated 1,1-Diarylalkanol Radical Cations Bearing α-Cyclopropyl Groups. The Competition between <i>O</i>-Neophyl Shift and C−Cyclopropyl β-Scission in the Intermediate 1,1-Diarylalkoxyl Radicals
directly observed by time-resolved spectroscopy. The product distributions observed in the reactions of 1•+ and 2•+ under these conditions (cyclopropylphenylketone, cyclopropyl(4-methoxyphenyl) ketone, and 4-methoxybenzophenone from 1•+; cyclopropyl(4-methoxyphenyl) ketone and 4,4‘-dimethoxybenzophenone from 2•+) have been rationalized in terms of a water-induced competition between O-neophyl shift and C−cyclopropyl
Hydride Reduction by a Sodium Hydride-Iodide Composite
作者:Pei Chui Too、Guo Hao Chan、Ya Lin Tnay、Hajime Hirao、Shunsuke Chiba
DOI:10.1002/anie.201600305
日期:2016.3.7
Sodium hydride (NaH) is widely used as a Brønsted base in chemical synthesis and reacts with various Brønsted acids, whereas it rarely behaves as a reducing reagent through delivery of the hydride to polar π electrophiles. This study presents a series of reduction reactions of nitriles, amides, and imines as enabled by NaH in the presence of LiI or NaI. This remarkably simple protocol endows NaH with
The Effect of Ring Substitution on the <i>O</i>-Neophyl Rearrangement of 1,1-Diarylalkoxyl Radicals. A Product and Time-Resolved Kinetic Study
作者:Carla S. Aureliano Antunes、Massimo Bietti、Gianfranco Ercolani、Osvaldo Lanzalunga、Michela Salamone
DOI:10.1021/jo0502448
日期:2005.5.1
A product and time-resolved kinetic study of the effect of ringsubstitution on the reactivity of 1,1-diarylalkoxyl radicals has been carried out. The radicals undergo an O-neophyl shift to give the isomeric 1-aryl-1-aryloxyalkyl radicals from which the corresponding aromatic ketones are formed. The rearrangement rate constants are influenced by ringsubstitution, increasing in the presence of electron-withdrawing