Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

Beilstein Journal of Organic Chemistry

Miriam Schulte¹  Susanne Thiele¹  Navid Ramezanian¹  Dhananjaya Sahoo¹  Adelheid Godt¹ 

[1] Bielefeld University, Faculty of Chemistry, Universitätsstr. 25, D-33615 Bielefeld, Germany;

关键词: alkyne protecting group;    carbometalation;    C–C coupling;    phenyleneethynylene;    polar tagging;   

DOI  :  10.3762/bjoc.6.57

来源: DOAJ

【 摘 要 】

One important access to monodisperse (functionalized) oligoPPEs is based on the orthogonality of the alkyne protecting groups triisopropylsilyl and hydroxymethyl (HOM) and on the polar tagging with the hydroxymethyl moiety for an easy chromatographic separation of the products. This paper provides an update of this synthetic route. For the deprotection of HOM protected alkynes, γ-MnO2 proved to be better than (highly) activated MnO2. The use of HOM as an alkyne protecting group is accompanied by carbometalation as a side reaction in the alkynyl–aryl coupling. The extent of carbometalation can be distinctly reduced through substitution of HOM for 1-hydroxyethyl. The strategy of polar tagging is extended by embedding ether linkages within the solubilising side chains. With building blocks such as 1,4-diiodo-2,5-bis(6-methoxyhexyl) less steps are needed to assemble oligoPPEs with functional end groups and the isolation of pure compounds becomes simple. For the preparation of 1,4-dialkyl-2,5-diiodobenzene a better procedure is presented together with the finding that 1,4-dialkyl-2,3-diiodobenzene, a constitutional isomer of 1,4-dialkyl-2,5-diiodobenzene, is one of the byproducts.

【 授权许可】

Unknown