The nature of the active species in bis(imino)pyridyl cobalt ethylene polymerisation catalysts

Studies on cobalt ethylene polymerisation catalysts bearing bis(imino)pyridine ligands strongly indicate that the activated species is not the anticipated cobalt(II) alkyl cation.     

Weak Cayley table groups III: PSL(2,q)

A weak Cayley table isomorphism is a bijection φ:G→H of groups such that φ(xy)～φ(x)φ(y) for all x,y∈G. Here ～ denotes conjugacy. When G = H the set of all weak Cayley table isomorphisms φ:G→G forms a group 𝒲(G) that contains the automorphism group Aut(G) and the inverse map I:G→G,x?x^?1. Let 𝒲₀(G) = ?Aut(G),I?≤𝒲(G) and say that G has trivial weak Cayley table group if 𝒲(G) = 𝒲₀(G). We show that PSL(2,pⁿ) has trivial weak Cayley table group, where p≥5 is a prime and n≥1.     

A Note on “Conjugacy Classes Outside a Normal Subgroup”

In this article, we found a mistake in Theorem 3.6 in the article “Conjugacy classes outside a normal subgroup”, written by G. H. Qian, W. J. Shi, and X. Z. You, published in Communications in Algebra, 2004, 32(12):4809–4820. We correct it here.     

Highly Emissive Far Red/Near‐IR Fluorophores Based on Borylated Fluorene–Benzothiadiazole Donor–Acceptor Materials

Stille, Suzuki–Miyaura and Negishi cross‐coupling reactions of bromine‐functionalised borylated precursors enable the facile, high yielding, synthesis of borylated donor–acceptor materials that contain electron‐rich aromatic units and/or extended effective conjugation lengths. These materials have large Stokes shifts, low LUMO energies, small band‐gaps and significant fluorescence emission >700 nm in solution and when dispersed in a host polymer.     

A Brønsted acid mediated cascade enone synthesis from aldehydes containing a tethered propargylsilane

MeSO3H effects the intramolecular allenylation of a series of aldehydes 1 to provide allenyl alcohol product 3 as a single diastereoisomer. Cyclization proceeds rapidly at -78 degrees C. However, when the reaction is performed at room temperature, aldehyde 1 provides enone product 7 instead. A mechanism for the formation of this product is proposed in which the initially formed allenyl alcohol 3 undergoes dehydration to provide an allyl carbocation, which is trapped with water, thereby installing the enone.     

Untersuchung von Getreideprodukten und Backwaren

Ohne Zusammenfassung     

Preparation of 4-Retinamidophenyl- and 4-Retinamidobenzyl-C-glycosyl and C-Glucuronosyl Analogues of the Glucuronide of 4-Hydroxyphenyl-Retinamide as Potential Stable Cancer Chemopreventive Agents

Abstract

Glucuronide metabolites of retinoic acid and its analogues have been suggested to be active cancer chemopreventive analogues of the parent molecules. However, these metabolites are susceptible to β-glucuronidase and acid-catalyzed cleavage and it is not clear whether these carbohydrate conjugates must be hydrolyzed back to the parent molecule to show activity. Thus, the multistep syntheses of stable C-glycosyl and C-glucuronosyl analogues of the known glucuronide metabolite of the breast cancer chemopreventive agent 4-hydroxyphenylretinamide (4-HPR) are outlined. The chemical and enzymatic stability of these compounds has been evaluated relative to the glucuronide of 4-HPR.     

Fusions of Character Tables and Schur Rings of Abelian Groups

If the character table of a finite group H satisfies certain conditions, then the classes and characters of H can fuse to give the character table of a group G of the same order. We investigate the case where H is an abelian group. The theory is developed in terms of the S-rings of Schur and Wielandt. We discuss certain classes of p-groups which fuse from abelian groups and give examples of such groups which do not. We also show that a large class of simple groups do not fuse from abelian groups. The methods to show fusion include the use of extensions which are Camina pairs, but other techniques on S-rings are also developed.