62256-41-1Relevant articles and documents
An organocatalytic method for the synthesis of some novel xanthene derivatives by the intramolecular Friedel-Crafts reaction
Yildiz, Tülay,Kü?ük, Hatice Ba?pinar
, p. 16644 - 16649 (2017/03/24)
An efficient organocatalytic method for the synthesis of new substituted 9-arylxanthenes (2a-2u) starting from diarylcarbinol compounds with an arenoxy group (1a-1u) has been developed using the intramolecular Friedel-Crafts reaction. The substrates were
Ruthenium-based metathesis catalysts, precursors for their preparation and their use
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Paragraph 0080-0082, (2014/05/20)
The invention is directed to ruthenium-based metathesis catalysts of the Grubbs-Hoveyda type. The new 2-aryloxy-substituted ruthenium catalysts described herein reveal rapid initiation behavior. Further, the corresponding styrene-based precursor compounds are disclosed. The catalysts are prepared in a cross-metathesis reaction starting from styrene-based precursors which can be prepared in a cost-effective manner. The new Grubbs-Hoveyda type catalysts are suitable to catalyze ring-closing metathesis (RCM), cross metathesis (CM) and ring-opening metathesis polymerization (ROMP). Low catalyst loadings are necessary to convert a wide range of substrates including more complex and critical substrates via metathesis reactions at low to moderate temperatures in high yields within short reaction times.
Fast olefin metathesis: Synthesis of 2-aryloxy-substituted Hoveyda-type complexes and application in ring-closing metathesis
Kos, Pavlo,Savka, Roman,Plenio, Herbert
supporting information, 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%.
