Regioselectivity in the C-acylation of 2(3h)-benzoxazolones

Unequivocal synthetic routes towards 5- and 6-acyl-2(3H)-benzoxazolones are described. Comparison of the physicochemical properties of the compounds obtained by direct acylation under various Friedel-Crafts reaction conditions always leads to the conclusion that 6-acyl derivatives are the only isolated products. This observation contradicts previously published results

Effect of L-penicillamine Hydantoin, and Analog of Glutathione, On Rat-liver Glutathione-peroxidase, Reductase and Transferase Reactions

In soluble fractions prepared from rat liver homogenates, L-penicillamine hydantoin appeared to be, on the basis of SH consumption measurements, a substrate for glutathione peroxidase but not transferase reactions. When glutathione is incubated with rat liver soluble proteins in the presence of penicillamine hydantoin, formation of oxidized glutathione is inhibited. Calculations from Lineweaver-Burk plots point out that inhibition by L-penicillamine hydantoin of the peroxide-dependent oxidations of glutathione is mixed, since both apparent K(m) and V(max) values are modified. Preincubation of rat liver soluble proteins with L-penicillamine hydantoin led to a progressive inactivation of glutathione peroxidase. The kinetics of this inactivation process with respect to time and inactivator concentration were studied. Inclusion in the preincubation mixture of SH-containing molecules such as dithiothreitol, L-cysteine or glutathione protected the enzyme against inactivation. However, none of these molecules and neither hydantoin, Triton X-100, phenol, nor dialysis could reverse the enzyme from inactivated to activated form. Mitochondrial glutathione peroxidase was inhibited and inactivated by L-penicillamine hydantoin to the same extent as its cytosolic counterpart. Modifications by penicillamine hydantoin of various subcellular markers enzymes (lactate dehydrogenase, N-acetyl beta-glucosaminidase, arylsulfatase C, butyryl-CoA dehydrogenase, lauryl-CoA and glycolate oxidases) were of weak amplitude consisting of either inhibition, inactivation or stimulation

Subcellular-distribution of Glycolyltransferases in Rodent Liver and Their Significance in Special Reference To the Synthesis of N-glycolylneuraminic Acid

The enzymic synthesis, transfer, and utilization of glycolyl-CoA (i.e. 2-hydroxyacetyl-CoA) have been studied in rat and mouse livers. On the one hand, these tissues contain the enzyme activities allowing the synthesis of glycolyl-CoA from fatty acids (palmitate omega-hydroxylase, omega-hydroxypalmitoyl-CoA synthetase, and mitochondrial beta-oxidation of omega-hydroxypalmitoyl-CoA) and 3-hydroxypyruvic acid (oxidation by intact mitochondria). On the other hand, three types of glycolyltransferase activities can be demonstrated in rodent livers, depending on either carnitine, glucosamine, or glucosamine-6-phosphate. The subcellular distributions of these glycolyltransferase activities are similar to those of the corresponding acetyltransferase counterparts. Concerning carnitine glycolyltransferase, the activity is widely distributed in the subcellular fractions, pointing out its occurrence in most cell compartments. By contrast, the glucosamine and glucosamine-6-phosphate glycolyltransferase activities were located preferentially in the microsomal fraction. The condensation between glycolyl-CoA and glucosamine (or glucosamine-6-phosphate) raises the interesting question of the nature and the role of the resulting glycolylglucosamine molecule, especially in an alternative N-glycolylneuraminic acid synthesis pathway

AlCl3-DMF complex as catalyst in the Friedel-Craft reaction. The reactivity of anhydrides and chlorides of dicarboxylic acids.

This paper reports different examples of Friedel-Crafts acylation of various substrates with dicarboxylic acid chlorides (phthalic, isophthalic, and malonyl synthons) in the presence of the AlCl3-DMF complex as catalyst. When we reacted 2(3 H)-benzothiazolone with phthalic anhydride in the presence of the AlCl3-DMF complex as catalyst, in addition to the product of 6-substitution, 4-(2-carboxybenzoyl) 2(3 H)-benzothiazolone was obtained as a contaminant. This is the first product ever obtained with a 4-substitution in the acylation of 2(3 H)-benzothiazolone