title: Synthesis of dibenzo[g,p]chrysenes from bis(biaryl)acetylenes via sequential ICl-induced cyclization and Mizoroki-Heck coupling.
abstract: We report a facile synthesis of functionalized dibenzo[g,p]chrysenes via initial ICl-promoted cyclization of bis(biaryl)acetylenes, followed by the Mizoroki-Heck coupling reaction. This new approach works well for various bis(biaryl)acetylenes to afford dibenzo[g,p]chrysenes bearing various functionalities. With substrates of one special type including 4'-methoxy-2-ethynylbiphenyls, we found that the ICl treatment led to ipso cyclization to give bicyclic spirocyclohexadienones. In the presence of MeOH/H2SO4, these spiroketone products undergo rearrangement to give 9-iodophenanthrenes through a selective 1,2-alkenyl migration. We prepared various 4'-methoxy-2-ethynylbiphenyl compounds to show the generalization of such an ipso cyclization and 1,2-alkenyl shift. This ipso-cyclization approach can be extended to the preparation of dibenzo[g,p]chrysenes.
authors.affiliation: Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Chia-Wen
authors.initials: CW
authors.lastname: Li
authors.forename: Cheng-I
authors.initials: CI
authors.lastname: Wang
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Liao
authors.forename: Rupsha
authors.initials: R
authors.lastname: Chaudhuri
authors.forename: Rai-Shung
authors.initials: RS
authors.lastname: Liu