Hydrotalcite catalysed [4+2] cycloaddition reactions of nitroso- and azo-alkenes
作者:Américo Lemos、João Paulo Lourenço
DOI:10.1016/j.tetlet.2009.01.045
日期:2009.3
The generation of nitroso- and azo-alkenes and their [4+2] cycloaddition reactions with furan and ethyl vinyl ether, producing dihydro-1,2-oxazines and tetrahydropyridazines, by the use of catalytic Mg:Al 3:1 hydrotalcite, is described. The absence of an organic solvent, the catalytic quantities of Ht required together with its regeneration and reuse, may be regarded as environmentally friendly, greener
Reactions of azoalkenes derived from hydrazones of ethyl bromopyruvate with electron rich alkenes and heterocycles
作者:Simon J. Clarke、Thomas L. Gilchrist、Américo Lemos、Tony G. Roberts
DOI:10.1016/s0040-4020(01)80992-3
日期:1991.7
Three hydrazones of ethyl bromopyruvate, the dinitrophenylhydrazone 2a, the toluene-4-sulphonylhydrazone 2b and the t-butoxycarbonylhydrazone 2c, have been reacted with a series of nucleophilic alkenes and heterocycles in the presence of sodium carbonate. Azoalkenes 3 are presumed as intermediates and adducts have been isolated. The azoalkenes derived from hydrazones 2a and 2c are found to be useful