404-24-0Relevant articles and documents
Water catalyzed hydrolysis of p-nitrotrifluoroacetanilide and trifluoroacetanilide. Carbonyl 18O-exchange does not accompany the water reaction
Slebocka-Tilk,Rescorla, Christopher G.,Shirin, Salma,Bennet, Andrew J.,Brown
, p. 10969 - 10975 (1997)
The water catalyzed hydrolyses of p-nitrotrifluoroacetanilide (3) and trifluoroacetanilide (8) were studied at various pH's and temperatures. The activation parameters for the water reactions of 3 and 8 are: ΔH = 14.4 ± 0.6 and 11.7 ± 0.3 kcal/mol and ΔS = -36.1 ± 1.8 and -52.3 ± 0.7 calmol·K, respectively. These are consistent with reactions that involve considerable restriction of degrees of freedom of the solvent/substrate in the transition state. A proton inventory analysis of the rate constants for hydrolysis of 3 in media of different mole fraction D2O indicates the process involves two or more protons in flight or undergoing loosening of their bonding in the transition state. 18O-Labeled amides were subjected to the hydrolytic conditions for various times up to 3 half-times of hydrolysis and recovered. Mass analysis showed that the 180 content in the recovered amide did not change during the course of the reaction. All the data support a process where the rate-limiting step for the water reaction involves a concerted or nearly concerted formation of a diol which undergoes subsequent C-N cleavage in preference to OH expulsion.
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McBee,Burton
, p. 3902 (1952)
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Rochat,W.V.,Gard,G.L.
, p. 4173 - 4176 (1969)
Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
supporting information, p. 5022 - 5037 (2021/05/04)
Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
Meta Selective C-H Borylation of Sterically Biased and Unbiased Substrates Directed by Electrostatic Interaction
Chaturvedi, Jagriti,Haldar, Chabush,Bisht, Ranjana,Pandey, Gajanan,Chattopadhyay, Buddhadeb
supporting information, p. 7604 - 7611 (2021/05/26)
An electrostatically directed meta borylation of sterically biased and unbiased substrates is described. The borylation follows an electrostatic interaction between the partially positive and negative charges between the ligand and substrate. With this strategy, it has been demonstrated that a wide number of challenging substrates, especially 4-substituted substrates, can selectively be borylated at the meta position. Moreover, unsubstituted substrates also displayed excellent meta selectivity. The reaction employs a bench-stable ligand and proceeds at a milder temperature, precluding the need to synthesize a bulky and sophisticated ligand/template.
