Laboratorium für Organische Chemie, ETH-Zürich , Hönggerberg, HCI, CH-8093 Zürich, Switzerland.
J Org Chem. 2014 Jan 3;79(1):426-31. doi: 10.1021/jo402440m. Epub 2013 Dec 11.
The formal [2 + 2] cycloaddition-retroelectrocyclization reaction was employed as the key transformation to obtain donor-substituted, π-conjugated polycyanohexa-1,3,5-trienes (TCHTs and PCHTs) and polycyanoocta-1,3,5,7-tetraenes from donor-substituted tetracyanobuta-1,3-dienes (TCBDs) and electron-rich alkynes. These push-pull-substituted oligoene chromophores were also accessed in good yield from tetracyanoethylene and donor-substituted alkynes by using a one-pot protocol. All bis-(N,N-dialkylanilino) donor-substituted push-pull trienes and tetraenes showed better electron-accepting potency and lower HOMO-LUMO gaps than the corresponding TCBDs, as evidenced by optical and electrochemical studies.
采用形式上的[2+2]环加成-反电环化反应作为关键转化，从供电子取代的四氰基丁二烯（TCBD）和富电子炔烃获得供电子取代的π共轭聚氰基己-1,3,5-三烯（TCHTs 和 PCHTs）和聚氰基辛-1,3,5,7-四烯。通过使用一锅法，这些推-拉取代的齐聚物生色团也可以从四氰乙烯和供电子取代的炔烃中以良好的收率获得。所有双-（N,N-二烷氨基）供电子取代的推-拉三烯和四烯都表现出比相应的 TCBD 更好的电子接受能力和更低的 HOMO-LUMO 能隙，这可以通过光学和电化学研究得到证明。
