Several novel crownlike exomethylene paracyclophanes were efficiently synthesized via an intramolecular palladium-catalyzed benzannulation of conjugated bis-enynes. A method for the efficient synthesis of bis-enynes 8, bearing an oligo(oxyethylene) linkage, was developed by utilizing a two-step procedure from commercially available and inexpensive ethylene glycols. A remarkable complete reversal of reactivity of ambident dilithiated nucleophile 4 toward triflate 7 in the presence of 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) was found.
ASJC Scopus subject areas
- Organic Chemistry