13546-92-4Relevant articles and documents
TEMPERATURE AND SOLVENT EFFECTS IN WITTIG REACTIONS
Aksnes, Gunnar,Berg, Terje Jonny,Gramstad, Thor
, p. 79 - 84 (2007/10/03)
The rates of the Wittig reactions between 4-nitrobenzaldehyde and five stabilized phosphoranes, Ph3P=CHC(O)R, where R = OMe, OPh, NPh2, Me, and Ph, are studied in benzene, dimethylformamide (DMF), and methanol, at 25, 35, and 45 deg C.The activation energies, E, when plotted as function of the corresponding activation entropies, ΔS(excit.), are found in two different regions in the E - ΔS(excit.) diagram, approximately described by two parallel lines, one belonging to the reactions in benzene and DMF, the other to the reactions in methanol.The differences in the activation parameters in aprotic and protic solvents are most likely a consequence of strong H-bonding in protic solvents.Reaction mechanisms in aprotic and protic solvents are discussed. - Key words: Stabilized phosphoranes; 4-nitrobenzaldehyde; Wittig reaction; temperature and solvent effects
AMINO- OR GUANIDINO-PHENYLPROPIONIC ACID DERIVATIVES
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, (2008/06/13)
Amino-or guanidino-phenylpropionic ester derivatives represented by the formula: STR1 wherein R is--NH 2 or STR2 R 1 is hydrogen or a lower alkyl group, and R 2 is an unsubstituted or a lower-alkyl-, carboxyalkyl-, lower-alkoxy-, lower-alkoxycarbonyl-or h