An efficient method for the synthesis of novel CF(3)-substituted tetrahydro-1,7-naphthyridines including cyclic α-amino acid derivatives has been developed. The method is based on unusual cyclobutene ring-opening of bicyclo[4.2.0]octa-1,6-dienes with pyrrolidine to afford the corresponding 1,5-diketones followed by their heterocyclization. A convenient one-pot procedure has been also elaborated starting from readily available trifluoromethylated 1,6-allenynes.
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http://dx.doi.org/10.1021/jo301501r | DOI Listing |
J Org Chem
November 2024
Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana 506004, India.
The thermal electrocyclic ring opening of fused -cyclobutene to ,-diene is prohibited according to the Woodward-Hoffmann (WH) rules; nonetheless, experiments provide firm evidence for their formation. However, the mechanism, electronic structure, and behavior during the reaction are ambiguous. Herein, we attempt to gain insights into the mechanism of thermal ring opening in four -heterocycles containing a conjugated diene as the core skeleton.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Department of Chemistry and Chemical Biology, Cornell University, 122 Baker Laboratory, Ithaca, New York 14853, USA.
Materials formed by the ring-opening metathesis polymerization (ROMP) of cyclic olefins are highly valued for industrial and academic applications but are difficult to prepare free of metal contaminants. Here we describe a highly efficient metal-free ROMP of cyclobutenes using hydrazine catalysis. Reactions can be initiated via in situ condensation of a [2.
View Article and Find Full Text PDFGrubbs 3rd-generation (G3) pre-catalyst-initiated ring-opening metathesis polymerization (ROMP) remains an indispensable tool in the polymer chemist's toolbox. Tricyclononenes (TCN) and tricyclononadienes (TCND) represent under-explored classes of monomers for ROMP that have the potential to both advance fundamental knowledge (, structure-polymerization kinetics relationships) and serve as practical tools for the polymer chemist (, post-polymerization functionalization). In this work, a library of TCN and TCND imides, monoesters, and diesters, along with their -norbornene counterparts, were synthesized to compare their behaviors in G3-initiated ROMP.
View Article and Find Full Text PDFChemphyschem
August 2024
Department of Chemistry, University of Manchester, Manchester, M13 9PL, Great Britain.
Identifying the main physicochemical properties accounting for the course of a reaction is of utmost importance to rationalize chemical syntheses. To this aim, the relative energy gradient (REG) method is an appealing approach because it is an unbiased and automatic process to extract the most relevant pieces of energy information. Initially formulated within the interacting quantum atoms (IQA) framework for a single reaction, here we extend the REG method to natural bond orbitals (NBO) analysis and to the case of two competitive processes.
View Article and Find Full Text PDFPolymers that degrade on demand have the potential to facilitate chemical recycling, reduce environmental pollution and are useful in implant immolation, drug delivery or as adhesives that debond on demand. However, polymers made by radical polymerization, which feature all carbon-bond backbones and constitute the most important class of polymers, have proven difficult to render degradable. Here we report cyclobutene-based monomers that can be co-polymerized with conventional monomers and impart the resulting polymers with mechanically triggered degradability.
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