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A new methodology has been developed for the synthesis of highly substituted nitrogen heterocycles such as pyrazines and imidazoles starting from α-diketones using phosphine supported ruthenium nanoparticles (RuNPs) as catalysts. Ruthenium nanoparticles Ru1-Ru4 supported with different phosphines such as dbdocphos, dppp, DPEphos, and Xantphos are screened, of which Ru1 and Ru4 are found to be the most active. Interestingly, aryl-substituted and alkyl-substituted α-diketones produced different products: namely, pyrazine and imidazoles, respectively. This reaction methodology has been applied to the synthesis of a key intermediate (2m) of the marine cytotoxic natural product Dragmacidin B and an estrogen receptor (2l). This work represents the first examples of pyrazines prepared by RuNPs.
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http://dx.doi.org/10.1021/acs.joc.6b03032 | DOI Listing |
J Org Chem
September 2025
State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China.
The first dearomative allylation of -(trialkylsilyl) benzyl chlorides with allyltributylstannane via RSi-Pd-π-benzyl intermediates is described. The reactions proceeded smoothly in the presence of a specific P,N hemilabile ligand to generate vinylsilanes bearing an allyl group in satisfactory to good yields. Systematic evaluation of phosphine ligands identified ESPmin and % Vbur (min) as key parameters correlating ligand structure with catalytic activity.
View Article and Find Full Text PDFDalton Trans
September 2025
Inorganic and Organometallic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany.
The reactivity of the redox-active metal crown complex (BDI*)MgNaN'' (VI), formally containing a Mg centre, with phosphine chalcogenides, RPCh (Ch = O, S, Se, Te; R = Me, Et) was investigated (BDI* = HC[BuCN(DIPeP)] with DIPeP = 2,6-EtCH-phenyl). While all RPCh reagents could be reduced, only the heavier ones led to clean reduction to S, Se and Te anions which were captured in the metalla-cycle. The smaller S anion can be stabilized by the tetrametallic MgNa-crown but the larger Se and Te require a pentametallic MgNa-crown.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
The C-H functionalization of arenes mediated by well-defined bis(phosphine)-supported organometallic iron(III) complexes is described. One-electron oxidation of -(depe)Fe(CH) (depe = 1,2-bis(diethylphosphino)ethane) generated the corresponding isolable iron(III) dimethyl derivative that was unstable toward Fe-CH homolysis. Oxidation of the corresponding iron(II) bis(aryl) complex -(depe)Fe(tolyl) resulted in rapid reductive elimination of the biaryl with formation of iron(I).
View Article and Find Full Text PDFChem Asian J
September 2025
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India.
In this study, we report NNN pincer bis-imino pyridine-supported copper(II) catalysts for the sustainable, eco-friendly, and practical multi-component synthesis (MCS) of pyrazolines and pyrimidines driven by the acceptorless dehydrogenation of benzyl alcohols. Herein, we synthesize and characterize two well-defined phosphine-free NNN pincer-supported copper(II) complexes, C1 and C2, using IR, UV-vis, HRMS, and single-crystal XRD. Utilizing these complexes, we develop the first multi-component synthetic route for 1,3,5-trisubstituted pyrazolines (TriPyz) from the dehydrogenative coupling of renewable benzyl alcohols and aromatic ketones with phenyl hydrazine, generating ecologically benign HO and H as side products.
View Article and Find Full Text PDFChemistry
August 2025
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India.
In this report, we present a sustainable, eco-friendly, practical, and cost-effective one-pot three-component reaction for the synthesis of a diverse library of highly substituted pyrimidines from amidines, primary alcohols, and aromatic ketones, catalyzed by a cobalt(III) complex. The well-defined cobalt(III) complex [Co(III)BPMAP-O]ClO is derived from a redox-active phosphine-free, pentadentate mono-carboxamide ligand (BPMAP-H), and is formed in situ from various cobalt(II) sources, including CoCl·6HO, CoBr, Co(NO)·6HO, Co(OAc)·4HO via oxygen activation. Using aromatic ketones and benzyl alcohols, a wide range of 2,4,6-trisubstituted pyrimidines (TriPym) and 2,4,5,6-tetrasubstituted pyrimidines (TetraPym) were synthesized (119 examples) in isolated yields of up to 93%.
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