81141-06-2Relevant academic research and scientific papers
MIXED AROMATIC-ALIPHATIC ACETALS; THEIR PREPARATION, (1)H AND (13)C-NMR SPECTRA AND HYDROGENOLYSIS BY ETHEREAL SOLUTION OF CHLOROALANE
Dusek, Jiri,Sklenar, Vladimir,Jonas, Jaroslav
, p. 2912 - 2923 (2007/10/02)
The corresponding p-X-phenylisobutyl acetals of acetaldehyde (I), 2-(p-X-phenoxy)tetrahydropyrans (II), 2-(p-X-phenoxy)tetrahydrofurans (III), and cyclohexyl(p-X-phenyl)acetals of acetaldehyde (IV) were prepared by addition of p-X-substituted phenols to isobutyl vinyl ether, 2,3-dihydro-4H-pyran, 2,3-dihydrofuran, and cyclohexyl vinyl ether, respectively.The structures of acetals I-IV were confirmed by their (1)H and (13)C-NMR spectra.Diastereotopic protons of the methylene and geminal methyl groups are anisochronous in the (1)H-NMR spectra of acetals I. (13)C-NMR spectra of acetals IV demonstrate anisochronous behaviour of cyclohexane ring diastereotopic carbon atoms.The constants ?p+ for several groups calculated using (13)C-NMR spectra are: 1-isobutoxy-1-ethoxy- (-0.58), 2-tetrahydrofuryloxy- (-0.59), and 1-cyclohexyloxy-(1-ethoxy) (-0.57).Experimental relative rate constants of hydrogenolysis of acetals I and II by ethereal solution of chloroalane yield best correlations with ?p+ constants of the substituent X, providing the values ρ= -1.09 for compounds of the series I and II, respectively.The importance of these results for finding the rate determining step of the studied reaction is discussed.
