Substituted 5,6,11,12-Tetradehydrodibenzo[a,e]cyclooctenes: Syntheses, Properties, and DFT Studies of Substituted Sondheimer–Wong Diynes

Highly strained cyclic acetylenes 5,6,11,12-tetradehydrodibenzo­[a,e]­cyclooctenes (Sondheimer–Wong diynes) having various substituents on their benzene rings were synthesized successfully by one-pot treatment of the corresponding formyl sulfones with diethyl chlorophosphate/lithium hexamethyldisilazide (LiHMDS) and then lithium diisopropylamide (LDA). When mixtures of two types of formyl sulfones bearing different substituents were subjected to this protocol, the unsymmetrically substituted Sondheimer–Wong diynes could be synthesized in a stepwise manner by isolation of the heterocoupled vinyl sulfone intermediates followed by their treatment with LDA. The UV–vis absorption spectra and cyclic voltammograms of the substituted Sondheimer–Wong diynes were recorded. The electronic effect of substituents on the diynes was investigated in their click reactions and nucleophilic and electrophilic additions.