499-76-3Relevant articles and documents
Carboxylation of Phenols with CO2 at Atmospheric Pressure
Luo, Junfei,Preciado, Sara,Xie, Pan,Larrosa, Igor
supporting information, p. 6798 - 6802 (2016/05/11)
A convenient and efficient method for the ortho-carboxylation of phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2. The addition of a trisubstituted phenol has proved essential for the successful carboxylation of phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids.
Chalcone derivatives and drugs containing the same
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, (2008/06/13)
PCT No. PCT/JP97/01652 Sec. 371 Date Nov. 17, 1998 Sec. 102(e) Date Nov. 17, 1998 PCT Filed May 16, 1997 PCT Pub. No. WO97/44306 PCT Pub. Date Nov. 27, 1997This invention relates to chalcone derivatives represented by the following formula (1): wherein A represents a phenyl group, a quinolyl group or the like, W represents a vinylene group or the like, and R1 to R5 each independently represent a carboxyl, cyano, alkyloxycarbonyl or like group, or salts of the chalcone derivatives, and also to drugs containing them as effective ingredients. These compounds have excellent cys-LT receptor antagonism, and are useful as antiallergic agents or the like.
Reactivity in the Para Oxo Ketene Route of Ester Hydrolysis. The Effect of Internal Nucleophilicity and the Irrelevance of B Strain
Thea, Sergio,Cevasco, Giorgio,Guanti, Giuseppe,Kashefi-Naini, Nasrin,Willams, Andrew
, p. 1867 - 1872 (2007/10/02)
The hydrolysis of 2,4-dinitrophenyl (DNP) esters of substituted 4-hydroxybenzoic acids obeys the equation kobsd = (ka + kb->)/(1 + +>/Ka) and involves a para oxo ketene intermediate.The ka term fits a Broensted equation against the pK of the 4-hydroxybenzoate (log ka = 1.15pKa - 11.71) provided the 2,6-positions of the benzoate are free.The ka term for the 2,6-dimethyl-4-hydroxybenzoate ester is 1015-fold larger than that for the parent 4-hydroxybenzoate ester.An electronic effect due to different hydroxyl pKa's may be calculated from the above linear free energy relationship to contribute 1.6percent of the discrepancy.The other component of the discrepancy is ascribed to a preferred alignment of the ester in the 2,6-dimethyl case perpendicular to the plane of the aromatic ring. The fused ketene in the microscopic reverse reaction has a LUMO acceptor orbital perpendicular to the plane of the ring, in agreement with our conclusions.Force-field calculations of nonbonding interactions indicate no strain release in the elimination mechanism giving rise to ka.The dramatic (107-fold) enhancement of the apparent second-order rate constant for alkaline hydrolysis of the 2,6-dimethyl ester compared with that of the corresponding 2',4'-dinitrophenyl 4-methoxy-2,6-dimethylbenzoate is due mostly to the steric strain imposed in the tetrahedral transition state for the latter reaction.This strain is not sufficient, however, to cause the normal BAc2 mechanism in the alkaline hydrolysis of mesitoates to change to a "square planar" concerted process.
