TY - JOUR
T1 - Studies on the acetylation of 3,6-diamino-1H-pyrazolo[3,4-b]pyridine-5- carbonitrile derivatives
AU - Chioua, Mourad
AU - Soriano, Elena
AU - Samadi, Abdelouahid
AU - Marco-Contelles, J.
PY - 2010/7
Y1 - 2010/7
N2 - (Chemical Equation Presented) The acetylation reaction of the differently substituted 3,6-diamino-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile derivatives 1-6 is reported. The structure of the resulting acetamides has been investigated and confirmed by analytical, spectroscopic, and chemical transformations. From these studies, we conclude that, in general, under mild conditions, and using acetic anhydride, when free, the N(1)H moiety is a more reactive center respect to the C(3)NH2 and C(6)NH2 groups. This trend is reversed when no steric hindrance due to presence of a phenyl group at C4 drives the preferred acetylation to C(3)NH2, as it is evident by comparing the observed results from precursor 1 with 3. When N1 is blocked, the (C3)NH 2 group undergoes preferential acetylation over the (C6)NH 2 site, which only has been mono (or diacetylated) at reflux. Computational analyses based on DFT studies have been extensively used to explain the observed reactivities.
AB - (Chemical Equation Presented) The acetylation reaction of the differently substituted 3,6-diamino-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile derivatives 1-6 is reported. The structure of the resulting acetamides has been investigated and confirmed by analytical, spectroscopic, and chemical transformations. From these studies, we conclude that, in general, under mild conditions, and using acetic anhydride, when free, the N(1)H moiety is a more reactive center respect to the C(3)NH2 and C(6)NH2 groups. This trend is reversed when no steric hindrance due to presence of a phenyl group at C4 drives the preferred acetylation to C(3)NH2, as it is evident by comparing the observed results from precursor 1 with 3. When N1 is blocked, the (C3)NH 2 group undergoes preferential acetylation over the (C6)NH 2 site, which only has been mono (or diacetylated) at reflux. Computational analyses based on DFT studies have been extensively used to explain the observed reactivities.
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U2 - 10.1002/jhet.403
DO - 10.1002/jhet.403
M3 - Article
AN - SCOPUS:77954605354
SN - 0022-152X
VL - 47
SP - 861
EP - 872
JO - Journal of Heterocyclic Chemistry
JF - Journal of Heterocyclic Chemistry
IS - 4
ER -