Regioselective dehydrogenation of 3-keto-steroids to form conjugated enones using o-iodoxybenzoic acid and trifluoroacetic acid catalysis
摘要:
Mild and regioselective conversion of 3-keto-5 alpha- and 3-keto-5 beta-steroids (trans A/B- and cis A/B-ring juncture, respectively) to the corresponding enones (Delta(1)- and Delta(4)-3-ketones) by treatment with oiodoxybenzoic acid (IBX) catalyzed by trifluoroacetic acid (TFA) in DMSO, is described. The IBX-mediated reaction involved dehydrogenation of the alpha- and beta-hydrogen atoms of the 3-ketones to give the enones regioselectively in good isolated yields without concomitant formation of related dienones and trienones. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
Photo-oxidation reactions, sensitized by methylene blue, of various tertiary amines and alkaloids have been studied. An immonium ion is postulated as an intermediate in the formation of secondary amines and of some cyclization and dimerization products.
Facilitating Children's Understanding of Misinterpretation: Explanatory Efforts and Improvements in Perspective Taking
作者:Bradford H. Pillow、Clay Mash、Samuel Aloian、Valerie Hill
DOI:10.1080/00221320209598673
日期:2002.6
The authors investigated children's understanding of how mistaken beliefs can arise through misinterpretation of ambiguous information. Children (N = 91), aged 4 to 5 years, were given pre- and posttests on their ability to infer a puppet's interpretation of a restricted-view drawing after the puppet had been led to an erroneous expectation about the drawing's identity. Before the posttest, the children received either self-explanation training or other-explanation training in which they explained the source of their own or a puppet's misinterpretations of drawings; a control group received no training. The children who received training improved from pre- to posttest, and those who had practiced explaining misinterpretations by referring to previously viewed pictures or to features of a target picture showed the greatest improvement. These results indicate that learning to explain misinterpretations can help children recognize situations in which misinterpretations are likely to occur.
Janot,M.-M. et al., Bulletin de la Societe Chimique de France, 1961, p. 2109 - 2113
作者:Janot,M.-M. et al.
DOI:——
日期:——
Über Steroide und Sexualhormone (58. Mitteilung) Umwandlung von 17-Äthinyl-androstendiol-(3,17) in Pregnadienol-(3)