84277-04-3Relevant academic research and scientific papers
Asymmetric Hydrogenation of Unfunctionalized Tetrasubstituted Acyclic Olefins
Bachmann, Stephan,Bigler, Raphael,Denmark, Scott E.,Gosselin, Francis,Han, Chong,Hildbrand, Stefan,Mack, Kyle A.,Pfaltz, Andreas,Scalone, Michelangelo,Shen, Jeff,Tosatti, Paolo,Zhang, Haiming
supporting information, p. 2844 - 2849 (2020/02/05)
Asymmetric hydrogenation has evolved as one of the most powerful tools to construct stereocenters. However, the asymmetric hydrogenation of unfunctionalized tetrasubstituted acyclic olefins remains the pinnacle of asymmetric synthesis and an unsolved challenge. We report herein the discovery of an iridium catalyst for the first, generally applicable, highly enantio- and diastereoselective hydrogenation of such olefins and the mechanistic insights of the reaction. The power of this chemistry is demonstrated by the successful hydrogenation of a wide variety of electronically and sterically diverse olefins in excellent yield and high enantio- and diastereoselectivity.
Pharmacological inhibition of outwardly rectifying Cl- currents in rat peritoneal mast cells: A comparison of different stilbene derivatives
Roloff, Tim,Ziegler, Albrecht,Heber, Dieter,Seebeck, Joerg
, p. 81 - 88 (2007/10/03)
Diethylstilbestrol and other stilbene derivatives can provide some inhibition of the outwardly rectifying Cl- current (I (Cl-,OR)) in rat peritoneal mast cells. In order to elucidate structure-activity relationships of diethylstilbestrol, 12 stilbenes as well as 17β-estradiol and hexestrol were tested in rat peritoneal mast cells using the nystatin-perforated patch approach of the whole-cell patch-clamp technique. Since trans-stilbene showed no effect, the substituents of diethylstilbestrol must be of importance. The introduction of only one hydroxy group in trans-stilbene produced potent inhibition of the I(Cl-,OR) (IC 50: 3.3 μM). But in contrast, resveratrol with hydroxy groups at positions 4, 3′, and 5′ as well as methoxy substituted stilbene derivatives and 17β-estradiol were ineffective. On the other hand, hexestrol potently inhibited I(Cl-,OR) indicating that the aromatic ring systems can also be connected by an ethyl bridge. In summary, a hydroxy group at position 4 (or 4′) is a prerequisite for diethylstilbestrol- mediated inhibition of I(Cl-,OR).
Synthesis of isomeric benchrotrenic alkenes by Ti-induced carbonyl coupling reaction
Besancon, J.,Szymoniak, J.,Moise, C.
, p. 325 - 330 (2007/10/02)
The benchrotrenic ketones BctCOR (1) (Bct: Cr(CO)3C6H5; R = CH3 (a), C2H5 (b), n-C3H7 (c), n-C4H9 (d) undergo reductive alkene coupling reaction when treated with TiCl3/Li.The two isomeric forms of Bct(R)C=C(R)Bct (2) were isolated in the ratio Z/E = ca. 3:1.Decomplexation of 2 by iodine gave quantitatively the corresponding isomeric alkyl stilbenes C6H5(R)C=C(R)C6H5 (3).
Stereochemistry and Side Products in Reductive Coupling of Alkyl Aryl Ketones to 1,2-Dialkyl-1,2-diarylethylenes
Leimner, Juergen,Weyerstahl, Peter
, p. 3697 - 3705 (2007/10/02)
The reductive coupling of alkyl aryl ketones 1 - 3 and 7 - 9 by low valent titanium salts yields predominantly the (Z)-isomers of 11 - 13 and 17 - 19.Evidence is given by 1H NMR spectroscopy.This behavior can be explained by ?-complex formation of phenyl rings with Ti0.Severe steric hindrance, however, favors the (E)-isomers ( -> 14 and 15).Donor groups in p-position, particularly, give increasing amounts of pinacols, 23 - 27, which undergo rearrangement to the ketones 28 and 29.
