Emeraldicene Derivatives

Significance

The authors discovered that DMF can act as a reducing agent in ring-closing Heck cross-coupling reactions in the syntheses of ­emeraldicene derivatives. Substitution of DMF by acetonitrile allowed for high-yielding syntheses of emeraldicenes and their disubstituted analogues. Alkylation of emeraldicene by organolithium afforded only monosubstitution at the bay-position, rather than the 2-position of the thiophene moiety. This can be attributed to the lowest electron density of HOMO at the bay-positions of emeraldicene as revealed from DFT calculations, along with electrophilicity at the carbon center of the ­fulvene-type moiety.