1956-06-5Relevant articles and documents
Comparison of the kinetic specificity of subtilisin and thiolsubtilisin toward n-alkyl p-nitrophenyl esters.
Philipp,Tsai,Bender
, p. 3769 - 3773 (1979)
The p-nitrophenyl esters of straight-chain fatty acids were used as substrates of the enzyme subtilisin Novo (EC 3.4.4.16) and its chemically produced artificial enzyme thiolsubtilisin. Subtilisin and thiolsubtilisin pH--activity profiles were determined, and kinetic effects of the active site O-S substitution were observed. Among the substrates tested, both enzymes show highest specificity with p-nitrophenyl butyrate. It was also found that subtilisin is more sensitive to changes in substrate chain length than is thiolsubtilisin. Second-order acylation rate constants (k2/Ks) are remarkably similar for both enzymes. However, thiolsubtilisin deacylation rate constants and Km values are lower than analogous subtilisin constants. While thiolsubtilisin deacylation rate constants give a pH profile identical with that of subtilisin, the pH profile of thiolsubtilisin acylation rate constants shows an active site pK value lowered from the subtilisin pK of 7.15 and exhibits an inflection point at pH 8.45, which is absent in subtilisin.
Carboxylic Acid Deoxyfluorination and One-Pot Amide Bond Formation Using Pentafluoropyridine (PFP)
Brittain, William D. G.,Cobb, Steven L.
supporting information, p. 5793 - 5798 (2021/08/01)
This work describes the application of pentafluoropyridine (PFP), a cheap commercially available reagent, in the deoxyfluorination of carboxylic acids to acyl fluorides. The acyl fluorides can be formed from a range of acids under mild conditions. We also demonstrate that PFP can be utilized in a one-pot amide bond formation via in situ generation of acyl fluorides. This one-pot deoxyfluorination amide bond-forming reaction gives ready access to amides in yields of ≤94%.
Organocatalytic activation of alkylacetic esters as enolate precursors to react with α,β-unsaturated imines
Hao, Lin,Chen, Shaojin,Xu, Jianfeng,Tiwari, Bhoopendra,Fu, Zhenqian,Li, Tong,Lim, Jieyan,Chi, Yonggui Robin
supporting information, p. 4956 - 4959 (2013/10/22)
Asymmetric functionalization of alkylacetic esters and their derivatives is traditionally achieved via preformed enolates with chiral auxiliaries. Catalytic versions of such transformations are attractive but challenging. A direct catalytic activation of simple alkylacetic esters via N-heterocyclic carbene organocatalysts to generate chiral enolate intermediates for highly enantioselective reactions is reported.
Palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols
Luo, Fang,Pan, Changduo,Cheng, Jiang,Chen, Fan
supporting information; experimental part, p. 5878 - 5882 (2011/09/12)
A palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols to access aryl benzoate derivatives is described. The procedure tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, fluoro and bromo groups. Thus, it represents a practically alternative method to access aryl benzoate derivatives.
