Reductive Cleavage of Allyllic Ketals by an Arene-Catalysed Lithiation: A Simple and Direct Route to Masked Lithium Homoenolates
作者:Juan F Gil、Diego J Ramón、Miguel Yus
DOI:10.1016/s0040-4020(01)87023-x
日期:1994.3
The reaction of acrolein diethyl acetal 1 with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB; 2.5 mol %) in the presence of a carbonyl compound 2 in THF at 0°C leads, after hydrolysis with water, to the corresponding γ-coupling products 3 as a Z/E mixture, the Z-isomer being mainly the major one. When the final hydrolysis was carried out in acidic conditions
Organolithiums by reductive lithiation: the catalytic aromatic method versus the use of preformed aromatic radical-anions. Naphthalene can behave as a catalyst or an inhibitor
using aromaticradical-anions for reductivelithiation, the replacement of a C–heteroatom bond with a C–Li bond, have been compared with regard to yield and the mildness of reaction conditions required. It was found that the use of preformed radical-anions generally resulted in higher yields and milder reaction conditions than the ‘catalytic’ method in which catalytic amounts of the aromatic compound