The Mechanism of Halide Reductions with Lithium Aluminum Hydride. IV. Tracer Studies in the Reduction of Halohydrins<sup>1</sup>
作者:Ernest L. Eliel、Thomas J. Prosser
DOI:10.1021/ja01597a050
日期:1956.8
Diastereoselective formation of anellated tetrahydrofurans using a nitrate radical induced oxidative, self-terminating radical cyclization cascade
作者:Uta Wille、Lars Lietzau
DOI:10.1016/s0040-4020(99)00564-5
日期:1999.8
Addition of electrogenerated nitrate radicals to C=C triple bonds in the alkynyl ethers cis-7-9 and trans-8-9 yields anellated tetrahydrofurans 12-16 with high diasteroselectivity through a new type of an oxidative, self-terminating radical cyclization cascade. The reaction probably proceeds via an intramolecular, rate-determining hydrogen atom transfer in the vinyl radical of type 17a, and a subsequent diastereoselective 5-exo radical cyclization. Elimination of nitrogen dioxide terminates the reaction sequence. This reaction is a remarkable example for the creation of a C-O bond by intermolecular addition of an O-centered radical to a pi-system. (C) 1999 Elsevier Science Ltd. All rights reserved.
β-Hydrogen Elimination of Ionic Butylzinc Complexes
作者:Konrad Koszinowski、Christina Müller、Harald Brand、Julia E. Fleckenstein
DOI:10.1021/om300698b
日期:2012.10.22
Gas-phase experiments on deuterium-labeled BuZn-(TMEDA)(+) (TMEDA = N,N,N',N'-tetramethylethylenediamine) prove that the loss of butene from this species corresponds to a beta-H elimination. Quantum-chemical calculations corroborate this finding and furthermore predict that the fragmentations of related cationic butylzinc complexes as well as of Bu3Zn- follow similar mechanisms.