41649-14-3Relevant academic research and scientific papers
Retro Diels-Alder Reactions of 5,6-Disubstituted-7-oxabicyclo[2.2.1]hept-2-enes: Experimental and Density Functional Theory Studies
Manka, Jason T.,Douglass, Andrew G.,Kaszynski, Piotr,Friedli, Andrienne C.
, p. 5202 - 5206 (2000)
Several 5,6-disubstituted-7-oxabicyclo[2,2.1]hept-2-enes (1-4) were synthesized on ≥0.1 mol scale. The heat-induced retro Diels-Alder (rDA) decomposition of these derivatives was studied by thermal analysis, and the kinetics of the rDA were measured for 4. First-order rate constants (k = 1.91-14.2 x 10-5 s-1), measured at four temperatures between 124 and 150°C, were used to calculate Arrhenius activation parameters Ea (34.5 ± 0.5 kcal/mol) and In A (1.77 ± 0.03 x 104). The observed activation energy was significantly larger (by 9.5 kcal/mol) than that previously measured for the maleic anhydride adduct 1, and this was attributed to the difference in LUMO energies for the two dienophiles. Modeling of the activation parameters found for 4 with density functional theory (DFT) calculations for similar compounds 5 and 6 gave close quantitative correlations for ΔH?, ΔG?, ΔS?. The rDA reactions studied were found to be entropy-driven.
A new route to amino-2-propanol structures with adrenergic β-blocker activity using low valent titanium
Bermudez,Del Campo,Sinisterra,Llama
, p. 4137 - 4140 (2007/10/03)
Amino-2-propanol structures can be obtained by addition to dibenzyl acetals of in situ generated dihalocarbenes using LTV (Low Valent Titanium). This methodology can be used to obtain adrenergic β-blockers with amino-2-propanol structure. Tetrahalomethane are the best dihalocarbene precursors. The yields obtained using halofluromethanes can be increased by addition of carbontetrachloride. A process that can imply halogen transfer may be proposed.
