Diels–Alder cycloaddition of acetylene gas to a polycyclic aromatic hydrocarbon bay region

Abstract

The direct conversion of a polycyclic aromatic hydrocarbon bay region to a new, unsubstituted benzene ring by Diels-Alder cycloaddition of acetylene gas is reported for the first time. At 140 °C in dimethylformamide, under 1.8 atm pressure of acetylene gas, 7,14-dimesitylbisanthene is slowly converted to 7,14-dimesitylbenzo[ghi]bisanthene (21% conversion in 48 h).

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

“…5b, acetylene C 2 H 2 can be incorporated into a site with armchair configuration through the Diels-Alder reaction (reaction 1), followed by a re-aromatization step (reaction 2). Similar reactions between C 2 H 2 and polycyclic aromatic hydrocarbons in organic solvents have been recently shown and proposed as the basis for metal-catalyst-free synthesis of SWCNTs by Fort et al 34,35 Likewise, C 2 H 4 can also be incorporated into an armchair site through the Diels-Alder reaction (reaction 3). The C À C single bond created by reaction 3 can be converted into a double bond via a radical (CH 3 ?…”

Reversal of Clar's Aromatic‐Sextet Rule in Ultrashort Single‐End‐Capped [5,5] Carbon Nanotubes

“…The growing process was devised to take place by means of Diels‐Alder cycloaddition of ethyne molecules, or some synthetic equivalent, on the rim of the elongating CNT. Despite the many attempts developed so far, this kind of synthesis remains unaccomplished …”

Towards pi-extended cycloparaphenylenes as seeds for CNT growth: investigating strain relieving ring-openings and rearrangements

“…Specifically, two methods of growth from a small molecule template have garnered significant attention in the literature. The first is based on a Diels–Alder polymerization strategy, 10 – 15 while the second is an adaptation of known CNT production methods ( Fig. 2a and b ).…”

“…2a ), the reaction sequence begins with a [4 + 2] cycloaddition between the “bay region” of the template ( 1 ) and acetylene, or an acetylene equivalent. 10 – 15 Though this step temporarily breaks the aromaticity of the template structure ( 2 ), it will rearomatize spontaneously under the reaction conditions through a thermal extrusion of H 2 ( 3 ). This process could then continue ad infinitum with excess acetylene, since new “bay regions” are created as the reaction proceeds ( 4 ).…”