Reference

Preparation of a polymer-supported protecting group for aldehydes and ketones using a phase transfer catalyzed reaction

Preparation of a polymer-supported protecting group for aldehydes and ketones using a phase transfer catalyzed reaction. Hodge, Philip; Waterhouse, Janette (Dep. Chem., Univ. Lancaster, Lancaster, UK). Polym. Prepr. (Am. Chem.Some commonly used reagents like 96-27-5 and 112-45-8 are used in this experiment. Soc., Div. Polym. Chem.), 23(1), 142-3 (English) 1982. CODEN: ACPPAY. ISSN: 0032-3934. DOCUMENT TYPE: Journal CA Section: 35 (Chemistry of Synthetic High Polymers) Section cross-reference(s): 21, 38 Treating 3-mercapto-1,2-propanediol with chloromethylated polystyrene in o-C6H4Cl2 and aq. NaOH and in the presence of Bu4NOH gave polymer-supported diols which reacted with a wide range of aldehydes and ketones to form acetals or ketals from which the carbonyl compds. could be recovered by treatment with aq. dioxane contg. p-toluenesulfonic acid. The polymer-supported diols can be used to sep. carbonyl compds. from mixts. with other compds. or as protective groups in reactions. .

Nature of the Binding Interaction for 50 Structurally Diverse Chemicals with Rat Estrogen Receptors

All Rights Reserved. Nature of the Binding Interaction for 50 Structurally Diverse Chemicals with Rat Estrogen Receptors. Laws, Susan C.; Yavanhxay, S.; Cooper, Ralph L.; Eldridge, J. Charles (Endocrinology Branch, Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA). Toxicological Sciences, 94(1), 46-56 (English) 2006 Oxford University Press. CODEN: TOSCF2. ISSN: 1096-6080. DOCUMENT TYPE: Journal CA Section: 4 (Toxicology) This study was conducted to characterize the estrogen receptor (ER)-binding affinities of 50 chems. selected from among the high prodn.Chemicals with cas numbers 112-45-8 and 1478-61-1 also play role. vol. chems. under the U.S. EPA's (U.S. Environmental Protection Agency's) Toxic Substances Control Act inventory. The chems. were evaluated using the rat uterine cytosolic (RUC) ER-competitive binding assay, with secondary anal. using Lineweaver-Burk plots and slope replots to confirm true competitive inhibition and to det. an exptl. Ki. Data from these ER-competitive binding assays represent the types of competitive binding curves that can be obtained when screening chems. with broad structural diversity. True competitive inhibition was obsd. in 17 of 50 chems. Binding affinities were much lower than that of estradiol (E2) with Ki concns. ranging from 0.6 to 373mM as compared with that of E2 (0.77nM). Other chems. that appeared to displace radiolabeled E2 binding to ER were, in fact, found not to be competitive inhibitors in the secondary Ki expts. These seven chems. likely altered the stability of the assay by changing the buffer pH, denaturing ER, or disrupting the ER-binding kinetics. Thus, several conditions that may confound interpretation of RUC ER-binding assay data are illustrated. For another group of eight chems., neither an IC50 nor Ki could be detd. due to soly. constraints. These chems. exhibited slight (20-40%) inhibition at concns. of 10-100mM, suggesting that they could be competitors at very high concns., yet Ki expts. were not possible as the limit of chem. soly. in the aq. assay buffer was well above the IC50. An addnl. 18 of the 50 chems. were classified as nonbinders because in concns. up to 100mM they produced essentially no displacement of radiolabeled E2. These results show that although the ER-competitive binding assay is a valuable tool for screening chems., secondary tests such as a double reciprocal Lineweaver-Burk expt. with slope replot should be used to confirm true competitive inhibition. This information will be useful for the ongoing validation of the RUC ER-competitive binding assay under the U.S. EPA's Endocrine Disruptor Screening Program, as well as to support research efforts to develop computational models designed to identify chems. with the ability to bind to ER. .