Solid-Phase Synthesis of Asymmetrically Substituted “AB3-Type” Phthalocyanines

• Published in: Journal of organic chemistry Vol. 73; no. 13; pp. 5003 - 5007
• Main Authors: Erdem, S. Sibel, Nesterova, Irina V, Soper, Steven A, Hammer, Robert P
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 04.07.2008
• Subjects: Chemistry; Coloring Agents - chemical synthesis; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Indoles - chemical synthesis; Molecular Structure; Organic chemistry; Preparations and properties; Ethylene oxide polymer; Phthalocyanine; Chemical solution; Amidine; Nitrile; Purification; Asymmetric molecule; Cleavage; Hydrophilic compound; Solid phase; Chemical synthesis
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo800536v

Synthesis of phthalocyanines with asymmetrical substitution on the periphery is often difficult due the problems in purification of the phthalocyanine mixtures obtained. Using a poly(ethylene glycol) (PEG)-based support with a Wang-type linker, we have developed the synthesis of monohydroxylated, oligoethylene glycol substituted phthalocyanines utilizing an amidine-base-promoted phthalonitrile tetramerization reaction. The use of a hydrophilic support allows symmetrical phthalocyanine product formed in solution to be readily and completely removed by washing while leaving the “AB3” product on the support. Acid cleavage with 10% trifluoroacetic acid provides the pure unsymmetrically substituted Pc. This method was applied to several metallo Pcs. Additionally, methods to avoid premature reactions on-resin that give A2B2 products are provided.