TY - JOUR
T1 - New examples of specific base catalysis in mononuclear rearrangements of heterocycles found via a designed modification of the side chain structure
AU - Frenna, Vincenzo
AU - Marullo, Salvatore
AU - Macaluso, Gabriella
AU - D'Anna, Francesca
AU - Spinellib, Domenico
AU - Guernelli, Susanna
AU - Lanza, Camilla Zaira
PY - 2009
Y1 - 2009
N2 - To select suitable candidates for the occurrence of specific-base-catalysis in MRH of (Z)-hydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole we have designed a modification of the side-chain structure by linking a strong electron-withdrawing system to the hydrazono group. Thus we have synthesized the (Z)-semicarbazone (3d), the (Z)-phenylsemicarbazone (3e), and the (Z)-acetylhydrazone (3f) of the above oxadiazole and examined their kinetic behavior in dioxane/water in a large range of proton concentrations (pS + 4.0 14.5). In all the pS+ range examined only a base-catalyzed process has been evidenced (no uncatalysed path occurs). The behavior at the largest pS+ values (the reactivity tends to a limiting rate constant) and that at variable concentrations of buffer have furnished clear evidence for the occurrence of a specificbase- catalysed process, thus reaching the target proposed and confirming the prevision.
AB - To select suitable candidates for the occurrence of specific-base-catalysis in MRH of (Z)-hydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole we have designed a modification of the side-chain structure by linking a strong electron-withdrawing system to the hydrazono group. Thus we have synthesized the (Z)-semicarbazone (3d), the (Z)-phenylsemicarbazone (3e), and the (Z)-acetylhydrazone (3f) of the above oxadiazole and examined their kinetic behavior in dioxane/water in a large range of proton concentrations (pS + 4.0 14.5). In all the pS+ range examined only a base-catalyzed process has been evidenced (no uncatalysed path occurs). The behavior at the largest pS+ values (the reactivity tends to a limiting rate constant) and that at variable concentrations of buffer have furnished clear evidence for the occurrence of a specificbase- catalysed process, thus reaching the target proposed and confirming the prevision.
KW - Mononuclear rearrangement of heterocycles
KW - base catalysis
KW - kinetic measurements
KW - Mononuclear rearrangement of heterocycles
KW - base catalysis
KW - kinetic measurements
UR - http://hdl.handle.net/10447/36845
M3 - Article
VL - viii
SP - 125
EP - 144
JO - Arkivoc
JF - Arkivoc
SN - 1551-7004
ER -