112296-82-9Relevant academic research and scientific papers
Effect of High Pressure on the Kinetics and Selectivity of the Intramolecular Hetero Diels-Alder Reaction of an 1-Oxa-1,3-butadiene
Buback, Michael,Abeln, Johannes,Huebsch, Thomas,Ott, Christian,Tietze, Lutz F.
, p. 9 - 12 (2007/10/02)
The intramolecular hetero Diels-Alder reaction of the benzylidene-isoxazolone 3 giving the adducts 4 and 5 is studied in dichloromethane under high pressure up to 5 kbar.The kinetics is measured by on-line FT-IR spectroscopy up to 3 kbar.The cycloaddition shows a clear pressure-induced increase in diastereoselectivity.For the difference in activation volume ΔΔV(excit.) of the reactions affording the two diastereomers, a value of -(1.6 +/- 0.2) cm3*mol-1 is obtained.The activation volume ΔVcis(excit.) is determined to be -(19.4 +/- 0.5) cm3*mol-1 at 343 K.The activation enthalpy and entropy , as derived from the overall rate coefficient k measured at 1000 bar, are (62.9 +/- 1.7) kJ*mol-1 (at 343 K) and -(135 +/- 11) J*mol-1*K-1. - Key Words: Hetero Diels-Alder reactions, intramolecular/ High-pressure reactions/ Diastereoselectivity/ Pyrans/ 1-Oxa-1,3-butadiens/ Isoxazolones
Intramolecular Hetero-Diels-Alder Reaction of Alkylidene- and Benzylidenepyrazolones and Benzylideneisoxazolones. Investigations toward the Conformation of the Transition State
Tietze, Lutz F.,Brumby, Thomas,Pretor, Martina,Remberg, Gerd
, p. 810 - 820 (2007/10/02)
Stereochemical aspects of the intramolecular hetero-Diels-Alder reaction of hetero dienes are studied.Knoevenagel condensation of aromatic aldehydes 1, 12, 15,, and 21 with pyrazolones 8a-h and isoxazolone 17 gave the corresponding hetero dienes, e.g.,9a-
