A π-Extension Process from 9-Phosphaanthracene Leading to Phosphatetraphenes and Phosphatetracenes.

Extension of π-system with phosphinine (phosphorine, phosphabenzene) has been of interest because of the expected higher HOMO and lower LUMO levels compared with the corresponding carbon congeners. In this paper, a π-extension process based on the 9-phosphaanthracene skeleton was demonstrated by synthesizing 12-phosphatetraphene and 9-phosphabenzo[f]tetraphene by utilizing the deaminative aromatization pathway. Starting from 3,5-bis(trifluoromethyl)aniline, we developed the dibromotriarylmethane precursors containing the 3,5-bis(trifluoromethyl)-2-bromophenyl unit, which would be slightly effective to increase the steric congestion around the fragile P=C bonds incorporated in the fused polyaromatic skeletons. The bis-trifluoromethyl 12-phosphatetraphenes have been synthesized together with the mono-trifluoromethyl derivative, and the planar 12-phosphatetraphene skeleton was confirmed. On the other hand, the CF3 -substituted 9-phosphabenzo[f]tetraphene displayed a remarkably twisted fused five ring system leading to the wavy structures incorporating phosphinine. Also, synthetic study of 5-phosphatetracene using the bis(trifluoromethyl)phenyl unit was attempted and the incomplete elimination of the amine indicated labile characters of the observed phosphorus congener of tetracene. The findings of this study would be informative for developing heavier congeners of polyaromatic hydrocarbons (PAHs) as well as the trifluromethyl effects.

Regiocontrolled Heptafluoroisopropylation of Aromatic Halides by Copper(I) Carboxylates with Heptafluoroisopropyl-Zinc Reagents.

Copper(I)-mediated heptafluoroisopropylation of aryl halides (ArX: X = I, Br) is demonstrated using copper(I) carboxylates and a bis(heptafluoroisopropyl)zinc reagent Zn( i-C3F7)2(dmf)2, prepared from heptafluoroisopropyl iodide and diethylzinc. The air-tolerant solid heptafluoroisopropylzinc reagent is advantageous to conduct simple synthetic operations and successful to give the corresponding heptafluoroisopropyl arene derivatives via transmetalation to copper(I) center. The newly developed copper(I)-mediated heptafluoroisopropylation process can be advanced to the copper(I)-catalysis by silver carboxylate salts and complementary to the precedent radical-based processes.