Impurity D is proven to be formed in lactonization
and was found in all stress conditions applied, with maximal obtained degradation of 0.08%.
Studies on enantioselective lactonization
were performed for esters 2a-f of 3,3,6-trimethyl-4(E)-heptenoic acid (1) and chiral, enantiomerically pure alcohols a-f (Scheme 1).
The reaction was terminated by the addition of 20 [micro]L of 6N HCl, and the tube was allowed to stand at room temperature for 10 min to ensure lactonization
of the biosynthetic MVA at pH < 1.
In addition, sialic acids can be further O-acetylated , de-N-acetylated , sulfated , or modified by lactonization
From the hydrolysis of the ester bonds of ellagitannins, hexaidroxidifenoil units are formed, and these, in turn, undergo a process of spontaneous lactonization
leading to the formation of ellagic acid (EA) .
Babu, "Direct lactonization
of a-amino [gamma], [delta]-unsaturated carboxylic acid esters via olefin activation: stereo- and regioselective production of homoserine lactone scaffolds having contiguous stereocenters," Tetrahedron, vol.
The actual number is even higher because of additional biochemical processes such as epimerization and lactonization
Covering first synthetic methods then synthetic intermediates, they consider such topics as the metal-free oxidative lactonization
of carbohydrates using molecular iodine, the synthesis of glycosyl vinyl sulfones for bioconjugation, and lactose-modified triethoxysilane for modifying the surface of clay nanocomposites.
SL occurs as a mixture of compounds differing in their acetylation, lactonization
, and position of hydroxylation.
The stereoselective introduction of the hydroxyl group at C25 was dependent on the configuration at C23 of the lactone and thus, the hydroxyl group of the other configuration was introduced in the ester moiety before the lactonization
as shown in Fig.
is the critical first step in the disposition of the 3hydroxy-3-methylglutaryl-CoA reductase inhibitor atorvastatin.
After an additional incubation for 30 min at 37[degrees]C to allow for complete lactonization
of the product mevalonate, the mixture was passed over a 0.5 x 5-cm column containing 100-200 mesh Bio-Rex, chloride form (Bio-Rad), which was equilibrated with distilled water.