93391-88-9Relevant academic research and scientific papers
OXYGEN HETEROCYCLES BY SULPHUR YLIDE ANNULATION. THE REACTION OF DIMETHYLSULPHOXONIUM METHYLIDE ON ortho-HYDROXYBENZAL KETONES; A CASE OF ANNULATION LEADING TO A MIXTURE OF UNEXPECTED OXYGEN HETEROCYCLES
Bravo, Pierfrancesco,Fronza, Giovanni,Ticozzi, Calimero
, p. 93 - 102 (2007/10/02)
Mixtures of several oxygen heterocyclic compounds were obtained from the annulation reaction promoted by dimethylsulphoxonium, methylide, 2, on ortho-hyroxybenzal ketones 1a-h, besides the 1,2-disubstituted cyclopropanes produced by the insertion of the methylene on the activated double bond.We isolated four 2,3-dihydrobenzofurans differently substituted on position three, namely 3-(2'-oxoalkyl)-2,3-dihydrobenzofurans, 5, arising by the usual annulation reaction; 3--2,3-dihydrobenzofurans, 8, generated by the insertion of the whole ylide molecule on substrates 1; 3--2,3-dihydrobenzofurans, 10; finally 3--2,3-dihydrobenzofurans, 17, deriving from 1 by insertion of three methylene units.Besides the above-mentioned compounds, we also isolated the 2-(2'-hydroxyphenyl)-3,6-dihydro-6H-pyrans, 15, containing two further methylene units than substrates 1.The complex reactions responsible for the formation of the different products are described.
OXYGEN HETEROCYCLES BY SULPHUR YLIDE ANNULATION: REACTION OF o-HYDROXYBENZALKETONES WITH DIMETHYLOXOSULPHONIUM METHYLIDE
Bravo, Pierfrancesco,Ticozzi, Calimero
, p. 713 - 716 (2007/10/02)
Beside the expected cyclopropanes IV and 2,3-dihydrobenzofuranes V, 2-(o-hydroxyphenyl)-2,3-dihydro-6H-pyrans X and 3-substituted-2,3-dihydrobenzofurans XII arise by transfer of methylenes, through the quinone methide intermediates IX, from dimethyloxosulphonium methylide on o-hydroxybenzalketones I.
