Synthèse du benzoyl-3 chromanol-4 et du benzoyl-3 2H-chromène

Reaction between phenylvinylketone and salicylaldehyde under basic conditions gave a mixture of 3-benzoyl-4-chromanol and 3-benzoyl-2H-chromene. Their structures were determined on the basis of analytical and spectroscopic data.     

Peroxydation du dihydro-2,3 4H pyranne et du dihydro-2,3 furanne. Etude de réactivités

Free radical reactions of unsaturated O-heterocycles with t-butyl hydroperoxide in the presence of cuprous salt gives peroxides. Their analysis leads to the determination of reactivities in H-abstraction. Allylic hydrogen is ten times more reactive than hydrogen in the α position of the heteroatom.     

Décomposition du percarbonate de O,O-t-butyle et O-isopropényle en solution: Acétonylation des esters,acides et nitriles

The Free-Radical Decomposition of O,O-t-Butyl and O-Isopropenyl Peroxycarbonate in Solution: the Acetonylation of Esters, Acides and Nitriles The free-radical decomposition of O, O-t-butyl and O-isopropenyl peroxycarbonate in substratres possessing mobile H-atoms (S? H) consists mainly in an induced chain process leading to acetonylated derivatives of the solvent. Fairly good yields are obtained but teh acetonylation of functional substrates often gives mixtures of isomers. In the case of methyl acetate, the acetonylation occurs on the C-atoms adjacent to the carbonyl (acylox moiety) and to the O-atom (alkox moiety). However, the relative amounts of the isomeric products depend on the concentration of the peroxycarbonate solutions; at lowest concentration, methyl 4-oxopentanoate (acyloxy moiety) is obtained selectively. It is assumed that the free radicals issued from the solvent are able to abstract H-atoms of other molecules of solvent before adding to the double bond of the peroxycarbonate; the more the peroxycarbonate solution is diluted the more the transfers from the C-atom adjacent to the carbonyl to the radicals adjacent to the O-atom are favoured. In the case of methyl alkanoates, H-transfers from the α-C-atoms to β-radicals of teh acyloxy moiety may account for the orientation of the process. Owing to similar H-transfer processes, the acetonylation of functional esters, of acids and nitriles is selective in most cases.