15780-45-7Relevant academic research and scientific papers
Synthesis in the Isocamphane Series, XVI. The Regioselectivity of Some Lewis Acids in the Catalyzed Diels-Alder-Reaction of Cyclopentadiene and Mesityloxide
Bachner, Johann,Huber, Ulrike,Buchbauer, Gerhard
, p. 679 - 682 (1981)
The regioselectivity of 9 Lewis acids in the catalyzed Diels-Alder-reaction of cyclopentadiene and mesityloxide is described and the endo:exo-ratio of 1a and 1b determined by quantitative HPLC- and 1H-NMR-measurements.The reaction mixture of 1a + 1b normally contains more of the endo epimer 1a, e.g. 3:1 for 1a:1b, and is therefore in agreement with the endo rule, only TiCl4 favors the exo epimer 1b. - Keywords: Diels-Alder reaction; Endo:exo ratio; Endo rule; Lewis acids; Regioselectivity
PREPARATION DE THIOCETONES ACYCLIQUES α-INSATUREES. DIMERISATION REGIOSELECTIVE EN 4H-DITHIINE-1,3
Beslin, P.,Lagain, D.,Vialle, J.,Minot, C.
, p. 3839 - 3846 (2007/10/02)
α-Unsaturated acyclic thioketones 6 a-d were prepared by a retro-Diels-Alder reaction using flash thermolysis technique.They were detected at low temperature (blue coloured pyrolysate) but dimerize in solution as soon as the temperature rose to -60o (case 6 a-c) and -20o (case 6 d).The structure of 6 d was established by UV and NMR spectra taken at -60o.Dimeric products were proved to be 4H-1,3 dithiin by spectral data and by univocal synthesis of 7 c and 7 d from the corresponding monomeric ketone. 1-3 Dithiin 7 d was isomerized at 190o into the thermodynamic isomer (8).This observed orientation of dimerisation agrees with theorical results obtained from molecular frontier orbital calculations.
