The Diels–Alder Reaction for the Synthesis of Polycyclic Aromatic Compounds

Abstract

The Front Cover shows a variety of dienophiles used in the synthesis of functionalized polycyclic aromatic hydrocarbons over the past decade via the Diels‐Alder reaction. Being discovered almost a century ago, this powerful synthetic method can be used for construction of new materials for organic electronics – one of the modern challenges of organic chemistry. Linear or angular, planar or curved, molecular or polymeric – the product scope is vast and will broaden even more with further development of new diene and dienophile components. More information can be found in the Minireview by P. A. Zaikin et al.

Preparation of a Key Tetraene Precursor for the Synthesis of Long Acenes

“…Acenes, molecules comprising linearly fused benzene rings, have attracted a lot of interest for a long time and have also experienced a renewed interest [1,2] in the past decade for potential applications in molecular electronics, [3,4] spintronics [5] and plasmonics. [6] However, the preparation of acenes longer than pentacene faces two main difficulties.…”

Fluorinated Phenanthrenes as Aryne Precursors: PAH Synthesis Based on Domino Ring Assembly Using 1,1‐Difluoroallenes

“…Arynes have a formal triple bond within their six‐membered ring, thus making them useful tools for the synthesis of fused benzene ring structures . However, with the exception of didehydronaphthalenes and didehydrophenanthrenes, the synthetic uses of these types of π‐extended arynes have been still limited …”

Supramolecular Diversity of Oxabicyclo[2.2.2]octenes Formed between Substituted 2H-Pyran-2-ones and Vinyl-Moiety-Containing Dienophiles

“…The Diels-Alder reaction, mechanistically classified as a [4+2] cycloaddition belonging to the larger group of pericyclic reactions, is one of the crucial synthetic tools for the construction of novel C-C bonds [1,2], gaining importance in all its varieties, including (organo)catalytic and enantioselective versions [3,4]. Cycloadditions are highly versatile reactions as a broad range of starting dienes and dienophiles (alkenes or alkynes) can be used.…”

“…Symmetry codes for endo-3a: (i) -x + 1, -y + 2, -z + 2; for endo-3b: (i) -x, -y + 1, -z + 1; (ii) x -1, y + 1, z; (iii) -x + 1, -y + 1, -z + 1; for endo-3c: (i) -x + 1, -y, -z; (ii) x +1 2 , -y, -z -1 2 ; for endo-3d: (i) -x, -y + 1, -z, (ii)iv) x, -y + 1, z + 1 2 ; for endo-3e•6a: (i) -x, -y + 1, -z + 2; (ii) -x + 1, -y + 1, -z + 2, (iii) -x + 1, -y + 1, -z + 1; for exo-3e: (i) -x, -y + 2, -z + 1, (ii) -x, -y + 2, -z + 2; for exo-3f:(i) -x + 1, -y + 1, -z + 2, (ii) x + 1, y + 1, z + 1, (iii) -x + 1, -y + 1, -z + 1; for 4a: (i) x, y -1 2 , -z + 3/2, (ii) -x + 1, -y + 2, -z + 2.In compound endo-3b, hydrogen-bonded centrosymmetric tetramer is present, formed via a combination of N1-H29• • • O10 and N2-H30• • • O2 i interactions with the graph-set motif R 4 4(18). In this tetramer, molecule A forms a hydrogen bond through the amide NH group acting as a hydrogen bond donor with the carbonyl oxygen atom of the amide group of molecule B acting as a hydrogen bond acceptor.…”