The hydrolysis of alkyl formates with leaving groups in the range pK(a) = 12-16 is catalyzed by substituted acetate anions. There is an increase in the Bronsted beta value for general base catalysis with decreasing pK(a) of the leaving alcohol and a complementary increase in -beta(lg) with decreasing pK(a) of the catalyzing base, both of which are consistent with a value of p(xy) = partial derivative beta/-pK(lg) = partial derivative beta(lg)/-partial derivative pK(BH) congruent-to 0.11. This result supports a class n mechanism of general base catalysis, in which a proton is abstracted from the nucleophilic water molecule by the base catalyst in the transition state; it is not consistent with the kinetically equivalent class e mechanism of electrophilic catalysis by general acids of a reaction with hydroxide ion, by proton donation to the leaving alcohol. Solvent deuterium isotope effects in the range k(H2O)/k(D2O) = 3.6-5.3 for the buffer-independent reaction and 2.5-2.8 for catalysis by CH3COO- support concerted proton transfer and O-C bond formation. The secondary isotope effect for catalysis of the hydrolysis of LCOOMe by acetate ion is k(D)/k(H) = 1.05. Both nucleophilic and general base mechanisms of catalysis by acetate anions are observed for the hydrolysis of substituted phenyl formates with leaving groups of pK(a) = 7.1 -10.1. A small value of beta = 0.12 for general base catalysis of the hydrolysis of phenyl formate and p-methylphenyl formate represents catalysis of the addition of water by hydrogen bonding of water to the base catalyst. On the other hand, a larger value of beta = 0.35 and a decrease in k(H2O)/k(D2O) to 1.2 were observed for general base catalysis of the hydrolysis of p-nitrophenyl formate. It is suggested that the increase in beta with decreasing pK(lg) (an apparent ''anti-Hammond effect'') may be accounted for by a change in mechanism, from catalysis of a stepwise reaction of phenyl and p-methylphenyl formates to concerted general base catalysis of formyl transfer to water for the reaction of p-nitrophenyl formate.
[EN] WATER SOLUBLE ESTERS OF [N-(4-AMINO-2-BUTYNYL)] WITH ANTICANCER ACTIVITY<br/>[FR] ESTERS HYDROSOLUBLES DE [N-(4-AMINO-2-BUTYNYL)] PRESENTANT UNE ACTIVITE ANTICANCEREUSE
申请人:SALAMA ZOSER B
公开号:WO2005095369A1
公开(公告)日:2005-10-13
The present invention relates to water soluble esters of [N-(4-amino-2-butynyl)] or 4-(N-substituted amino)-2-butynyl-1-esters and methods for production of said esters and the use of the esters for treatment of cancer.