42370-06-9Relevant academic research and scientific papers
Syntheses in the Isocamphane Series, XXXIX. Improvement of the Diels-Alder Reaction of Cyclopentadiene with Mesityloxide by means of Ultrasound and a New Synthesis of Dehydrocamphene
Buchbauer, G.,Spreitzer, H.,Bauer, I.,Knobel, H.
, p. 921 - 926 (1994)
The synthesis of the valuable terpenic synthon 2-acetyl-3,3-dimethylbicyclohept-5-ene is clearly improved concerning the yield and especially the reaction time by applying ultrasound on the Diels-Alder reaction of cyclopentadiene with mesityl oxide.A new synthesis of dehydrocamphene and its odour impression is described. - Keywords: 2-Acetyl-3,3-dimethylbicyclohept-5-ene; Camphene; 5,5-Dimethyl-6-methylenebicyclohept-2-ene; Isocamphane derivatives; Isocamphodiene; Norborn-5-ene derivatives; Odour; Sonification; Ultrasound chemistry.
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 (2007/10/02)
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.
Cycloadditions of Allyl Cations, 26. Norbornene Derivatives from Cyclopentadiene and 2,4-Dimethyl-3-penten-2-ol in an Acidic Two Phase System. A Stepwise Diels-Alder-like Cyclization
Vathke-Ernst, Heidrun,Hoffmann, H. M. R.
, p. 1464 - 1475 (2007/10/02)
2,4-Dimethyl-3-penten-2-ol (1) and cyclopentadiene react in an acidic two phase system at 0 - 25 deg C in several steps yielding epimeric norbornenylcarbinols (endo-4 and exo-4) and at least three isomeric allylcyclopentenols (2a, b, c), whereas allylcyclopentadienes (3a, b) and norbornene-type olefins (endo-5, exo-5, and 6) are formed in traces under these conditions.All bicyclic products of this reaction were synthesized independently.On subjecting the pure product norbornenylcarbinols (endo-4 and exo-4) to the acidic, two phase reaction conditions at slightly elevated temperature, i. e. 50 deg C, some epimerization occurs and the norbornene-type olefins (exo-5, endo-5, and 6) are formed in addition to allylcyclopentadienes (3a, b), allylcyclopentenols (2a, b, c), nortricyclic alkohol 7, and tricyclic ether 8.Independently, the forward reaction was traced by subjecting the isomeric allylcyclopentenols 2b, c to the acidic, two phase reaction conditions at 50 deg C: once again, endo/exo bicyclization gave the olefins 5 and 6 as well as alkohols 4 and 7.Hence, a stepwise Diels-Alder-like cyclization is proposed to account for the norbornene-type alcohols and bicyclic olefins, which are formed from the acid promoted reaction of cyclopentadiene and 1.
