37563-31-8Relevant articles and documents
Efficient and versatile catalysis for β-alkylation of secondary alcohols through hydrogen auto transfer process with newly designed ruthenium(II) complexes containing ON donor aldazine ligands
Premkumar, Periyasamy,Manikandan, Rajendran,Nirmala, Muthukumaran,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
, p. 3065 - 3079 (2017)
A new series of ruthenium(II) carbonyl complexes, [RuCl(CO)(EPh3)2(L1-2)] (1–4) (E?=?P or As; H2L1?=?salicylaldazine, H2L2?=?2-hydroxynaphthaldazine), have been assembled from ruthenium(II) precursors [RuHCl(CO)(EPh3)3] and bidentate ON donor Schiff base ligands (H2L1-2). Both ligands and their new ruthenium(II) complexes have been characterized by elemental analyses, spectroscopic methods (UV, IR, NMR (1H, 13C, 31P) as well as ESI mass spectrometry. The molecular structures of H2L1 and 1 have been confirmed by single crystal X-ray diffraction. Based on the above studies, an octahedral coordination geometry around the metal center has been proposed for 1–4. To investigate the catalytic effectiveness of 1–4, the complexes have been used as catalysts in β-alkylation of secondary alcohols with primary alcohols and synthesis of quinolines. The effect of solvent, time, base, catalyst loading, and substituent of the ligand moiety on the reaction was studied. Notably, 1 was a more efficient catalyst toward alkylation of a wide range of alcohols and quinolines synthesis. The reusability of the catalyst was checked and the results showed up to six catalytic runs without significant loss of activity.
Synthesis and catalytic applications of ruthenium(ii)-phosphino-oxime complexes
Francos, Javier,Menéndez-Rodríguez, Lucía,Tomás-Mendivil, Eder,Crochet, Pascale,Cadierno, Victorio
, p. 39044 - 39052 (2016/06/01)
In this work, the preparation of the first ruthenium complexes containing a phosphino-oxime ligand is presented. Thus, the reaction of cis-[RuCl2(DMSO)4] (3) with 2.4 equivalents of 2-Ph2PC6H4CH=NOH (1) in refluxing THF led to the clean formation of the octahedral ruthenium(ii) derivative cis,cis,trans-[RuCl2{κ2-(P,N)-2-Ph2PC6H4CH=NOH}2] (5), whose structure was unambiguously confirmed by means of a single-crystal X-ray diffraction study. Complex 5 could also be synthesized from the reaction of the dimer [{RuCl(μ-Cl)(η6-p-cymene)}2] (4) with an excess of 1 in refluxing toluene. Treatment of 4 with 2 equivalents of 1, in CH2Cl2 at r.t., allowed also the preparation of the half-sandwich Ru(ii) derivative [RuCl{κ2-(P,N)-2-Ph2PC6H4CH=NOH}(η6-p-cymene)][PF6] (6). In addition, complexes 5 and 6 proved to be active catalysts for the rearrangement of aldoximes to primary amides, as well as for the α-alkylation/reduction of acetophenones with primary alcohols, with the former showing the best performances in both processes.
Redesign of enzyme for improving catalytic activity and enantioselectivity toward poor substrates: Manipulation of the transition state
Ema, Tadashi,Nakano, Yasuko,Yoshida, Daiki,Kamata, Shusuke,Sakai, Takashi
supporting information; experimental part, p. 6299 - 6308 (2012/09/05)
Secondary alcohols having bulky substituents on both sides of the hydroxy group are inherently poor substrates for most lipases. In view of this weakness, we redesigned a Burkholderia cepacia lipase to create a variant with improved enzymatic characteristics. The I287F/I290A double mutant showed a high conversion and a high E value (>200) for a poor substrate for which the wild-type enzyme showed a low conversion and a low E value (5). This enhancement of catalytic activity and enantioselectivity of the variant resulted from the cooperative action of two mutations: Phe287 contributed to both enhancement of the (R)-enantiomer reactivity and suppression of the (S)-enantiomer reactivity, while Ala290 created a space to facilitate the acylation of the (R)-enantiomer. The kinetic constants indicated that the mutations effectively altered the transition state. Substrate mapping analysis strongly suggested that the CH/π interaction partly enhanced the (R)-enantiomer reactivity, the estimated energy of the CH/π interaction being -0.4 kcal mol-1. The substrate scope of the I287F/I290A double mutant was broad. This biocatalyst was useful for the dynamic kinetic resolution of a variety of bulky secondary alcohols for which the wild-type enzyme shows little or no activity. The Royal Society of Chemistry 2012.
