6972-81-2Relevant articles and documents
Fast olefin metathesis: Synthesis of 2-aryloxy-substituted Hoveyda-type complexes and application in ring-closing metathesis
Kos, Pavlo,Savka, Roman,Plenio, Herbert
, p. 439 - 447 (2013/05/21)
Four 1-(4-R-phenoxy)-2-ethenylbenzenes (R=NMe2, H, Cl, NO 2) 4a, 4b, 4c and 4d were reacted with the ruthenium complexes [RuCl2(NHC)(3-phenylindenylidene)(py)] in the presence of a protic resin to result in the formation of the respective Hoveyda-type complexes 5a-d {NHC=SIMes [1,3-bis(2,4,6-trimethylphenylimidazolin)-2-ylidene]} and 6a-d {NHC=SIPr [1,3-bis(2,6-diisopropylphenylimidazolin)-2-ylidene]} in 66-84% yield. The lower steric bulk and the decreased donation of the diaryl ether oxygen atoms in complexes 5 and 6 led to rapidly initiating precatalysts. The Ru(II/III) redox potentials of complexes 6 were determined (6a-d: ΔE=0.89-1.08 V). In the crystal structure of 5b two independent molecules were observed in the unit cell, displaying Ru-O distances of 226.6(4) and 230.5(3) pm. The catalytic performance of complexes 5 and 6 in various ring-closing metathesis (RCM) reactions was studied. Catalyst loadings of between 15-200 ppm are sufficient for the formation of >90% yield of the respective cyclic products. Complex 6b catalyzes the formation of N-protected 2,5-dihydropyrroles with up to TON 64,000 and TOF 256,000 h-1, of the N-protected 1,2,3,6- tetrahydropyridines with up to TON 18,200 and TOF 73,000 h-1 and of the N-protected 2,3,6,7-tetrahydroazepines with up to TON 8,100 and TOF 32,000 h-1 with yields ranging between 77 and 96%.
Synthesis of pentabromopseudilin and other arylpyrrole derivatives via Heck arylations
Schwalm, Cristiane S.,De Castro, Ilton B.D.,Ferrari, Jailton,De Oliveira, Fábio L.,Aparicio, Ricardo,Correia, Carlos Roque D.
supporting information; experimental part, p. 1660 - 1663 (2012/04/10)
Pentrabromopseudilin and other 2 and 3-arylpyrrole derivatives were synthesized through the Heck-Matsuda reaction involving endocyclic enecarbamates and N-protected 3-pyrrolines, respectively. The overall processes permitted an easy and efficient access t
Batchwise and continuous organophilic nanofiltration of Grubbs-type olefin metathesis catalysts
Schoeps, Dirk,Buhr, Kristian,Dijkstra, Marga,Ebert, Katrin,Plenio, Herbert
experimental part, p. 2960 - 2965 (2009/12/08)
A mass-tagged N-mesityl imidazolinium salt with four additional -CH 2NCy2 substituents was synthesized, leading to a molecular mass of nearly 1100 g mol-1 in the corresponding carbene ligand. This mass-tagged ligand was used to generate the respective Grubbs II and Grubbs-Hoveyda type complexes. The catalytic activity of the latter complex was tested in several olefin metathesis reactions and found to be slightly superior to that of the related N-mesityl based complex. In batchwise solvent resistant nanofiltration experiments the ruthenium complex dissolved in toluene and following a metathesis reactions was efficiently retained (>99.8%) by a single nanofiltration; the permeate contained less than 4 ppm of Ru. Equally efficient catalyst retention was observed in a membrane reactor utilized for the continuous synthesis of a RCM product.
