Double Diels−Alder Strategies to Soluble 2,9- and 2,9,6,13-Tetraethynylpentacenes, Photolytic [4 + 4] Cycloadditions, and Pentacene Crystal Packing

摘要: Four new classes of organic solvent soluble ethynylpentacene derivatives (2,9-, 2,10-, 2,6,9,13-, 2,6,10,13-) have been prepared by complementary, versatile, double Diels−Alder strategies. Functional groups on the A, C, and E rings can be manipulated to increase solubility, modulate electronics, alter solid-state packing. Cycloaddition reactions with diene 2 1,4,5,8-anthradiquinone (3) or ortho-quinodimethane 19 1-butyl-3-methylimidazolim iodide (18) as source (a significant improvement over NaI) benzoquinone (20) followed in situ aromatization afforded quinones 4, 5, 21, 22, respectively. For 2,9- 2,10- families, a one-pot desilylation/triflation was developed. Palladium(0) coupling reductive 2,9-di(triisopropylsilylethynyl)pentacene (10) 2,10-di(triisopropylsilylethynyl)pentacene (11), Photodimerization these pentacenes air-stable [4 + 4] cycloaddition pentacene precursors (tetrakisnap...