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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Calix[4]arenes with siloxanes bridging opposite rings
Paul F Hudrlik1, Anne M Hudrlik, Liping Zhang
1Department of Chemistry, Howard University, Washington, District of Columbia 20059, USA. phudrlik@howard.edu
The Journal of Organic Chemistry
|September 14, 2007
Summary
Novel calixarenes were synthesized by bridging opposite rings with a siloxane group. These compounds exhibited unique flattened cone conformations, offering new structural possibilities in calixarene chemistry.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Materials Science
Background:
- Calixarenes are versatile macrocyclic compounds with tunable properties.
- C-silylated calixarenes offer unique synthetic handles for further functionalization.
- Controlling the conformational flexibility of calixarenes is crucial for designing advanced materials.
Purpose of the Study:
- To synthesize novel calixarene derivatives with bridged structures.
- To investigate the conformational behavior of these new compounds.
- To explore the impact of siloxane bridging on calixarene conformation.
Main Methods:
- Treatment of C-silylated calixarenes with tetrabutylammonium fluoride (TBAF).
- Purification and characterization of the resulting bridged calixarenes.
- Nuclear Magnetic Resonance (NMR) spectroscopy for conformational analysis.
Main Results:
- Successful synthesis of novel calixarenes featuring a Si-O-Si siloxane bridge between opposite rings.
- Compounds 2, 15, and 19 were obtained, with compound 19 and derived phenol 20 showing mixtures of cone and partial cone conformations.
- Calixarenes 2 and 15, along with precursor 14 and components of 17, 19, and 20, adopted flattened cone conformations.
Conclusions:
- The siloxane bridging strategy effectively modifies calixarene structures.
- Flattened cone conformations are prevalent in these novel bridged systems.
- These findings contribute to the understanding of conformational control in calixarene chemistry.
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