6957-08-0Relevant articles and documents
Enantioselective photoredox catalysis enabled by proton-coupled electron transfer: Development of an asymmetric aza-pinacol cyclization
Rono, Lydia J.,Yayla, Hatice G.,Wang, David Y.,Armstrong, Michael F.,Knowles, Robert R.
supporting information, p. 17735 - 17738 (2014/01/06)
The first highly enantioselective catalytic protocol for the reductive coupling of ketones and hydrazones is reported. These reactions proceed through neutral ketyl radical intermediates generated via a concerted proton-coupled electron transfer (PCET) event jointly mediated by a chiral phosphoric acid catalyst and the photoredox catalyst Ir(ppy)2(dtbpy)PF6. Remarkably, these neutral ketyl radicals appear to remain H-bonded to the chiral conjugate base of the Bronsted acid during the course of a subsequent C-C bond-forming step, furnishing syn 1,2-amino alcohol derivatives with excellent levels of diastereo- and enantioselectivity. This work provides the first demonstration of the feasibility and potential benefits of concerted PCET activation in asymmetric catalysis.
Continuous preparation of arylmagnesium reagents in flow with inline IR monitoring
Brodmann, Tobias,Koos, Peter,Metzger, Albrecht,Knochel, Paul,Ley, Steven V.
experimental part, p. 1102 - 1113 (2012/08/27)
A newly developed microscale ReactIR flow cell was used as a convenient and versatile inline analytical tool for Grignard formation in continuous flow chemical processing. The LiCl-mediated halogen/Mg exchange reaction was used for the preparation of functionalized arylmagnesium compounds from aryl iodides or bromides. Furthermore, inline IR monitoring was used for the analysis of conversion and possible byproduct formation, as well as a potential tool for elucidation of mechanistic details. The results described herein indicate that the continuous flow systems are effective for highly exothermic reactions such as the Grignard exchange reaction due to fast mixing and efficient heat transfer.
Ni-catalysed, domino synthesis of tertiary alcohols from secondary alcohols
Berini, Christophe,Navarro, Oscar
, p. 1538 - 1540 (2012/02/16)
The use of in situ generated (NHC)-Ni catalytic species (NHC = N-heterocyclic carbene) allows for the synthesis, in short reaction times, of a variety of tertiary alcohols from secondary alcohols through a domino oxidation-addition protocol.
Rhodium(I)/diene-catalyzed addition reactions of arylborons with ketones
Liao, Yuan-Xi,Xing, Chun-Hui,Hu, Qiao-Sheng
supporting information; experimental part, p. 1544 - 1547 (2012/06/05)
Rh(I)/diene-catalyzed addition reactions of arylboroxines/arylboronic acids with unactivated ketones to form tertiary alcohols in good to excellent yields are described. By using C2-symmetric (3aR,6aR)-3,6-diaryl-1,3a,4,6a- tetrahydropentalenes as ligands, the asymmetric version of such an addition reaction, with up to 68% ee, was also realized.
Organocalcium Chemistry: Preparation and Reactions of Highly Reactive Calcium
Wu, Tse-Chong,Xiong, Heping,Rieke, R. D.
, p. 5045 - 5051 (2007/10/02)
A highly reactive form of calcium was prepared by the reduction of Ca(II) salts with preformed lithium biphenylide.Remarkably, this activated calcium undergoes oxidative addition to organic bromides, chlorides, or even fluorides to form the organocalcium reagents under very mild conditions in high yields.The resulting organocalcium compounds undergo Grignard-type reactions.Transmetalation with Cu(I) salts forms calcium cuprate reagents which undergo a variety of cross-coupling reactions.The activated calcium reacts with 1,3-dienes to yield the corresponding 2-butene-1,4-diylcalcium complexes.These bis-organocalcium reagents can undergo dialkylation reactions with α,ω-alkylene dihalides and dichlorosilanes to form the corresponding 3-, 5-, and 6-membered ring derivatives.Significantly, these reactions are highly stereospecific and regioselective.
Synthesis and Anticonvulsant Activity of 1-Phenylcyclohexylamine Analogues
Thurkauf, Andrew,Costa, Brian de,Yamaguchi, Shun-ichi,Mattson, Mariena V.,Jacobson, Arthur E.,et al.
, p. 1452 - 1458 (2007/10/02)
Thirty-eight analogues of 1-phenylcyclohexylamine (PCA), a phencyclidine (PCP) derivative, were examined for their activities in the mouse maximal electroshock (MES) seizure test and in a motor-toxicity assay.In addition, we determined the binding affinities of the compounds for PCP acceptor sites in rat brain membranes labeled with -1-piperidine.Many of the analogues were protective against MES seizures (ED50s of 4-41 mg/kg, ip) and all of these compounds caused motor toxicity.The potencies in the motor toxicity and MES seizure tests showed a moderate correlation with the affinities for PCP sites.Several analogues exhibited a greater separation of potencies in the motor toxicity and MES seizure tests than did the parent compound PCA.These were obtained by (i) 3-methylation of the cyclohexyl ring trans to the phenyl ring, (ii) methoxylation at the ortho position on the phenyl ring, and (iii) contraction of the cyclohexane ring to form the corresponding cyclopentane.
