π-Extended dibenzo[g,p]chrysenes

Abstract

Here, we report two series (denoted meta and para) of π-extended dibenzo[g,p]chrysenes (DBC) with different substituents (H, Me and OMe). These six novel compounds benefit from the presence of eight...

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Regioselectivity in the Scholl Reaction: Mono and Double [7]Helicenes

“…To prove that no nonhelical isomer was present in our mixture, the synthesis of compound M2 has been accomplished starting from the 2,7,10,15tetrabromodibenzo[g,p]chrysene S3. 23 As provided in the SI (Figure S4), the NMR spectrum of this compound is distinct, and no trace of this chemical shift pattern was observed in the double-helicene reaction.…”

“…The major and minor products were identified as the P,P/M,M ( 2 ) and M,P/P,M ( 3 ) configurations, respectively; note that 3 is ∼4.7 kcal/mol less stable than 2 (Figure S10, SI). To prove that no nonhelical isomer was present in our mixture, the synthesis of compound M2 has been accomplished starting from the 2,7,10,15-tetrabromodibenzo­[ g , p ]­chrysene S3 . As provided in the SI (Figure S4), the NMR spectrum of this compound is distinct, and no trace of this chemical shift pattern was observed in the double-helicene reaction.…”

“…DBC has been brominated in quantitative yield to afford the 3,6,11,14-tetrabromodibenzo[g,p]chrysene S2. 23 The Suzuki− Miyaura cross-coupling reaction of S2 with four equivalents of biphenyl boronic ester 4 has generated the important precursor 13 in 67% yield, which allowed us to carry out the final step, oxidative C−C bond formation using DDQ/MeSO 3 H in CH 2 Cl 2 at 0 °C, as shown in Scheme 2B. As expected by looking at the structure of the double [7]helicene derivatives, two different relative configurations (P,P/M,M and M,P/P,M) are synthetically feasible.…”

Effect of Internal Substituents on the Properties of Dibenzo[g,p]chrysene

“…Dibenzo­[ g , p ]­chrysene (DBC) 1 is a polycyclic aromatic hydrocarbon with D 2 symmetry with potential in diverse applications such as chemical sensors, organic semiconductors, − nanoporous materials, , and organic light-emitting diodes (Figure , left). Over time, various synthetic methods have been developed to produce DBC 1 and its peripherally functionalized derivatives, allowing their large-scale preparation. − DBC 1 adopts a chiral double-helicene − structure arising from steric repulsion in the cove region . Moreover, DBC 1 undergoes selective internal functionalization due to the high reactivity of the central carbon atoms. , Clar’s rule suggests the presence of a double bond between the internal carbons in the dominant resonance structure .…”