1777-59-9Relevant academic research and scientific papers
Ground-State Electron Transfer as an Initiation Mechanism for Biocatalytic C-C Bond Forming Reactions
Fu, Haigen,Lam, Heather,Emmanuel, Megan A.,Kim, Ji Hye,Sandoval, Braddock A.,Hyster, Todd K.
, p. 9622 - 9629 (2021/07/01)
The development of non-natural reaction mechanisms is an attractive strategy for expanding the synthetic capabilities of substrate promiscuous enzymes. Here, we report an "ene"-reductase catalyzed asymmetric hydroalkylation of olefins using α-bromoketones as radical precursors. Radical initiation occurs via ground-state electron transfer from the flavin cofactor located within the enzyme active site, an underrepresented mechanism in flavin biocatalysis. Four rounds of site saturation mutagenesis were used to access a variant of the "ene"-reductase nicotinamide-dependent cyclohexanone reductase (NCR) from Zymomonas mobiles capable of catalyzing a cyclization to furnish β-chiral cyclopentanones with high levels of enantioselectivity. Additionally, wild-type NCR can catalyze intermolecular couplings with precise stereochemical control over the radical termination step. This report highlights the utility for ground-state electron transfers to enable non-natural biocatalytic C-C bond forming reactions.
Copper-Catalyzed N-O Cleavage of α,β-Unsaturated Ketoxime Acetates toward Structurally Diverse Pyridines
Ding, Xiaojuan,Duan, Jindian,Fang, Zheng,Guo, Kai,Li, Zhenjiang,Mao, Yiyang,Rong, Binsen,Xu, Gaochen,Zhang, Lei,Zhu, Ning
supporting information, p. 2532 - 2542 (2020/03/13)
The copper-catalyzed [4 + 2] annulation of α,β-unsaturated ketoxime acetates with 1,3-dicarbonyl compounds for the synthesis of three classes of structurally diverse pyridines has been developed. This method employs 1,3-dicarbonyl compounds as C2 synthons and enables the synthesis of multifunctionalized pyridines with diverse electron-withdrawing groups in moderate to good yields. The mechanistic investigation suggests that the reactions proceed through an ionic pathway.
Tandem Wittig Reaction-Ring Contraction of Cyclobutanes: A Route to Functionalized Cyclopropanecarbaldehydes
Aitken, David J.,Caboni, Pierluigi,Cuccu, Federico,Frongia, Angelo,Luridiana, Alberto,Secci, Francesco,Serusi, Lorenzo
supporting information, (2019/10/08)
An original tandem reaction consisting of a Wittig reaction-ring contraction process between α-hydroxycyclobutanone and phosphonium ylides has been developed. Highly functionalized cyclopropanecarbaldehydes are obtained in good to high yield.
Catalytic Cyclooligomerization of Enones with Three Methylene Equivalents
Farley, Conner M.,Zhou, You-Yun,Banka, Nishit,Uyeda, Christopher
, p. 12710 - 12714 (2018/10/09)
Cyclic structures are highly represented in organic molecules, motivating a wealth of catalytic methods targeting their synthesis. Among the various ring-forming processes, cyclooligomerization reactions possess several attractive features but require addressing a unique challenge associated with controlling ring-size selectivity. Here we describe the catalytic reductive cocyclooligomerization of an enone and three carbene equivalents to generate a cyclopentane, a process that constitutes a formal [2 + 1 + 1 + 1]-cycloaddition. The reaction is promoted by a (quinox)Ni catalyst and uses CH2Cl2/Zn as the C1 component. Mechanistic studies are consistent with a metallacycle-based pathway, featuring sequential migratory insertions of multiple carbene equivalents to yield cycloalkanes larger than cyclopropanes.
Nonenzymatic Dynamic Kinetic Resolution of in situ Generated Hemithioacetals: Access to 1,3-Disubstituted Phthalans
Nath, Utpal,Chowdhury, Deepan,Pan, Subhas Chandra
supporting information, p. 1628 - 1633 (2018/03/21)
The first nonenzymatic DKR reaction of hemithioacetals is developed. Hemithioacetals were formed in situ via thiol addition and subsequently underwent an intramolecular oxa-Michael reaction. The scope of the reaction was quite broad ranging from aliphatic to aromatic substituents and 1,3-disubstituted-1,3-dihyroisobenzofuran products were obtained in good yields with moderate diastereoselectivities and high enantioselectivities. (Figure presented.).
Synthesis of trifluoromethyl-/cyclopropyl-substituted 2-isoxazolines by DBU-promoted domino reaction
Liu, Xiao-Dong,Ma, Hai-Yan,Xing, Chun-Hui,Lu, Long
, p. 1780 - 1783 (2017/07/27)
NTrifluoromethyl and cyclopropyl substituted 2-isoxazolines were synthesized via a DBU-promoted domino reaction of β-trifluoromethyl-/β-cyclopropyl-substituted enones with hydroxylamine. The domino reaction consists of a Michael addition and the followed cyclization. A wide range of 3-substituted 5-cyclopropyl-5- trifluoromethyl-2-isoxazolines were obtained in good to excellent yields under mild reaction conditions. The method could also apply to other trifluoromethyl-substituted enones.
Isothiourea-mediated one-pot synthesis of functionalized pyridines
Stark, Daniel G.,Morrill, Louis C.,Yeh, Pei-Pei,Slawin, Alexandra M. Z.,O'Riordan, Timothy J. C.,Smith, Andrew D.
supporting information, p. 11642 - 11646 (2013/11/06)
Acids to bases: The synthesis of 2,4,6-trisubstituted pyridines from (phenylthio)acetic acid and a range of α,β-unsaturated ketimines is reported. This process proceeds by intermolecular Michael addition/ lactamization, thiophenol elimination, and N- to O
Crossed intramolecular rauhut-currier-type reactions via dienamine activation
Marques-Lopez, Eugenia,Herrera, Raquel P.,Marks, Timo,Jacobs, Wiebke C.,Koenning, Daniel,De Figueiredo, Renata M.,Christmann, Mathias
supporting information; experimental part, p. 4116 - 4119 (2009/12/06)
The intramolecular Rauhut-Currier reaction creates a carbon-carbon bond between two tethered Michael acceptors. Previous asymmetric versions have relied on 1,4-additions of chiral nucleophilic catalysts. Herein, we Investigate a novel strategy that involves the formation of electron rich dienamines as key Intermediates. Our methodology provides an efficient entry to the iridoid framework.
New access to trisubstitutea 3-pyrrolines under phosphine catalysis
Schuler, Marie,Duvvuru, Deepti,Retailleau, Pascal,Betzer, Jean-Francois,Marinetti, Angela
supporting information; scheme or table, p. 4406 - 4409 (2009/12/26)
Conjugated dienes, properly activated by electron-withdrawing groups on both ends, are shown to be suitable substrates for phosphinepromoted organocatalytic processes. Their reactions with imines, under phosphine catalysis, afford a new and efficient synthetic approach to functionalized 3-pyrrolines.
Synthesis and characterization of transition metal (Hg(II), Ag(I) and Cd(II)) complexes of some new: Phosphorus ylides
Sabounchei, S. Javad,Jodaian, Vida,Nemattalab, Hassan
experimental part, p. 9 - 13 (2010/08/19)
Reaction of two new phosphorus ylides Ph3PCHCOC 10H7 (Y1) and Ph3PCHCOC 4H3S(Y2) with mercury(II) halides and a previously reported ylide (P-tolyl)3PCHCOOCH
