- Protodeboronation of (Hetero)Arylboronic Esters: Direct versus Prehydrolytic Pathways and Self-/Auto-Catalysis
-
The kinetics and mechanism of the base-catalyzed hydrolysis (ArB(OR)2→ ArB(OH)2) and protodeboronation (ArB(OR)2→ ArH) of a series of boronic esters, encompassing eight different polyols and 10 polyfluoroaryl and heteroaryl moieties, have been investigated by in situ and stopped-flow NMR spectroscopy (19F,1H, and11B), pH-rate dependence, isotope entrainment,2H KIEs, and KS-DFT computations. The study reveals the phenomenological stability of boronic esters under basic aqueous-organic conditions to be highly nuanced. In contrast to common assumption, esterification does not necessarily impart greater stability compared to the corresponding boronic acid. Moreover, hydrolysis of the ester to the boronic acid can be a dominant component of the overall protodeboronation process, augmented by self-, auto-, and oxidative (phenolic) catalysis when the pH is close to the pKaof the boronic acid/ester.
- Hayes, Hannah L. D.,Wei, Ran,Assante, Michele,Geogheghan, Katherine J.,Jin, Na,Tomasi, Simone,Noonan, Gary,Leach, Andrew G.,Lloyd-Jones, Guy C.
-
p. 14814 - 14826
(2021/09/13)
-
- TRIAZOLOPYRIDINE COMPOUNDS AND USES THEREOF
-
A compound of Formula (IA), or a pharmaceutically acceptable salt thereof, is provided that has been shown to be useful for treating a PRC2-mediated disease or disorder: wherein A, R6, R7 and R8 are as defined herein.
- -
-
Paragraph 00138
(2018/04/11)
-
- IMIDAZOPYRIMIDINE COMPOUNDS USEFUL FOR THE TREATMENT OF CANCER
-
A compound of Formula (IA), or a pharmaceutically acceptable salt thereof, is provided that has been shown to be useful for treating a PRC2-mediated disease or disorder: wherein A, R3, R4, R6, and R7 are as defined herein.
- -
-
Paragraph 00140
(2018/04/12)
-
- Base-Catalyzed Aryl-B(OH)2 Protodeboronation Revisited: From Concerted Proton Transfer to Liberation of a Transient Aryl Anion
-
Pioneering studies by Kuivila, published more than 50 years ago, suggested ipso protonation of the boronate as the mechanism for base-catalyzed protodeboronation of arylboronic acids. However, the study was limited to UV spectrophotometric analysis under acidic conditions, and the aqueous association constants (Ka) were estimated. By means of NMR, stopped-flow IR, and quenched-flow techniques, the kinetics of base-catalyzed protodeboronation of 30 different arylboronic acids has now been determined at pH > 13 in aqueous dioxane at 70 °C. Included in the study are all 20 isomers of C6HnF(5-n)B(OH)2 with half-lives spanning 9 orders of magnitude: a and Sδ values, kinetic isotope effects (2H, 10B, 13C), linear free-energy relationships, and density functional theory calculations, we have identified a mechanistic regime involving unimolecular heterolysis of the boronate competing with concerted ipso protonation/C-B cleavage. The relative Lewis acidities of arylboronic acids do not correlate with their protodeboronation rates, especially when ortho substituents are present. Notably, 3,5-dinitrophenylboronic acid is orders of magnitude more stable than tetra-and pentafluorophenylboronic acids but has a similar pKa.
- Cox, Paul A.,Reid, Marc,Leach, Andrew G.,Campbell, Andrew D.,King, Edward J.,Lloyd-Jones, Guy C.
-
supporting information
p. 13156 - 13165
(2017/09/26)
-
- Rh(I)-catalyzed decarboxylative transformations of arenecarboxylic acids: Ligand- and reagent-controlled selectivity toward hydrodecarboxylation or heck-mizoroki products
-
(Chemical Equetion Presentation) A Rh(I)-based catalyst system has been developed to promote three types of decarboxylative transformations of arenecarboxylic acids: (1) hydrodecarboxylation, (2) Heck-Mizoroki olefination, and (3) conjugate addition. Scopes of reactions (1) and (2) were studied, and the ligand and reagent dependence of selectivity was explored.
- Sun, Zhong-Ming,Zhang, Jing,Zhao, Pinjing
-
supporting information; experimental part
p. 992 - 995
(2010/06/16)
-
- A convenient synthesis of 4-alkoxy- and 4-hydroxy-2,6-difluoroanilines
-
Two independent synthetic pathways for the preparation of 4-methoxy, 4-benzyloxy and 4-hydroxy-2,6-difluoroanilines, versatile building blocks in medicinal chemistry, based on diazonium coupling or Curtius-type rearrangements are presented.
- Alonso-Alija, Cristina,Michels, Martin,Peilst?cker, Karen,Schirok, Hartmut
-
-
- Carboxylate derivatives comprising an ether group and liquid crystal composition comprising the same
-
A compound represented by the following general formula (I), a liquid crystal composition comprising the same, and a liquid crystal element using this liquid crystal composition. (wherein B1 and B2 represent independently a trans-1,4-cyclohexylene group o
- -
-
-
- An unexpected route to fluorinated anisoles
-
We found a new one-pot procedure for the synthesis of polyfluoroanisoles from polyfluoroanilines. The reaction involves aromatic nucleophilic substitution of o- or p-fluorine of benzenediazonium salt with methoxy group followed by reductive removal of the diazonium group.
- Takechi, Naoto,Fukai, Yasushi,Oka, Kazuyoshi,Huisgen, Rolf
-
-
- REACTION OF AROMATIC COMPOUNDS WITH NUCLEOPHILIC REAGENTS IN LIQUID AMMONIA IV.* THE NUCLEOPHILIC AND PROTOPHILIC ACTIVITY OF METHOXIDE AND HYDROXIDE IONS IN REACTIONS WITH POLYFLUORINATED AROMATIC COMPOUNDS
-
In the reaction of polyfluorinated derivatives of benzene with potassium methoxide in liquid ammonia a fluorine atom is substituted by a methoxy group.With potassium hydroxide reactions involving removal of a proton from a ring carbon atom take place preferentially.The possibility of polyfluoroarylation and methylation catalyzed by potassium hydroxide in polyfluorinated aromatic compounds, based on capture of the polyflurinated aryl anion by the electrophile, was demonstrated.
- Shtark, A. A.,Chuikova, T. V.,Shteingarts, V. D.
-
p. 960 - 967
(2007/10/02)
-