28547-22-0Relevant academic research and scientific papers
Effects of neutral and charged substituents on the infrared carbonyl stretching frequencies in phenyl and alkyl benzoates in DMSO
Nummert, Vilve,Piirsalu, Mare,Vahur, Signe,Toom, Lauri,Leito, Ivo,Koppel, Ilmar A.
, (2017)
The carbonyl infrared stretching frequencies for 57 meta-, para- and ortho-substituted phenyl benzoates, C6H5CO2C6H4-X and alkylbenzoates, C6H5CO2R, containing besides neutral substituents the charged substituents in phenoxy and alkoxy part in dimethyl sulfoxide (DMSO) have been recorded. The carbonyl stretching frequencies, νCO, for meta- and para-substituted phenyl esters of benzoic acids in the case of neutral substituents were found to correlate well with the substituent constants, σ°. The νCO values for ortho derivatives correlated with the inductive substituent constants, σI, only. The values of constants for charged substituents, σ°±, calculated on the basis of the νCO and the 13C NMR chemical shifts, δCO, in DMSO agree well with the σ°± values for the corresponding ion pairs reported by Hoefnagel and Wepster and those determined from the log k values of the alkaline hydrolysis in 4.4 M NaCl solution at 50 °C. Thus, the values of substituent constants for ion pairs of charged substituents estimated on the basis of aqueous data could be successfully used in non-aqueous solution (DMSO) simultaneously with neutral substituents in case the charged substituents were not completely ionized and are in ion pair form. Copyright
Dearomatising cyclisation of lithiated allyl phenyl ethers: The role of an oxazoline substituent
Harvey, Rebecca A.,Karlubíková, Ol'Ga,Parris, Sean,Clayden, Jonathan
, p. 4064 - 4066 (2013/07/26)
Treatment of 3-allyloxyphenyl oxazolines with organolithium bases leads to allyllithiums which undergo dearomatising cyclisation. The resulting dearomatised anions may be quenched with electrophiles to form partially saturated benzopyran derivatives.
Kinetic and structural consequences of the leaving group in substrates of a class C β-lactamase
Ahn, Yong-Mo,Pratt
, p. 1537 - 1542 (2007/10/03)
The class C β-lactamase of Enterobacter cloacae P99 is known to catalyze the hydrolysis of certain acyclic (thio)esters. Previous experiments have employed thioglycolate, m-hydroxybenzoate, and phenylphosphate leaving groups. The relative effectiveness of these leaving groups has now been quantitatively assessed by employment of a series of compounds with common acyl groups, and found to rank in the order phenylphosphate >m-hydroxybenzoate >thioglycolate. Structural models suggest that these leaving groups interact during acylation principally with Tyr 150, Lys 315, and Thr 316 of the β-lactamase active site. The positions of the leaving group carboxylates in these models is compared with those in published crystal structures of complexes of class C β-lactamases with β-lactams. The particular effectiveness of the acyl phosphate indicates the positions of two oxyanions that strongly interact with the active site. This information should be useful in the design of inhibitors of class C β-lactamases.
ANOMALOUS ORIENTATION EFFECTS DURING BENZOYLOXYLATIONS BY "SILVER BROMIDE DIBENZOATE"
Bryce-Smith, Derek,Isaacs, Neil S.,Tumi, Seddeg O.
, p. 1471 - 1472 (2007/10/02)
The solid complex formed from bromine and silver benzoate reacts with both arenes and alkenes to form aryl and alkyl benzoates, respectively.Highly unusual substituent effects are observed in the benzoyloxylations of arenes.Electron-withdrawing groups (e.g. -NO2, -CN,-CO-) on the aromatic ring facilitate reaction though directing the attacking reagent exclusively to the meta position.In alkanes, tertiary positions are most prone to attack.
