Thermische und photochemische Additionen von Dienophilen an Arene und deren Vinyloge und Hetero-Analoge; I

Newer investigations of the reactions of dienophiles with arenes and heteroarenes confirm older findings that usually [4+2]-cycloadditions and in special cases also [2+2]-cycloadditions occur. In light-induced reactions, the [2+2]-cycloadditions generally predominate; however, cycloadditions of a higher order (such as [4+4]-, [6+2]-, [6+4]-, [8+2]-, and [14+2]-cycloadditions) have also been observed. In vinylarenes (vinylogs of aromatic compounds, e.g. styrene), the extracyclic ethylene moiety together with an adjacent aromatic "double bond" can function as a diene system, and the reaction with dienophiles may frequently lead to the formation of 1:2 addition products besides the 1:1 addition products. An entirely different reaction type gives rise to 1:1-alternating copolymers of styrene and its derivatives with dienophiles; however, in the initial step of the copolymerization reaction diene addition products are probably involved. [2+2]-Cycloaddition is the favored type of photochemical reaction of vinylarenes with dienophiles. 1. Addition of Dienophiles to Aromatic Double-Bond Systems 1.1. Addition to Arenes and Related Cyclic Systems 1.1.1. Benzene and Derivatives, Cyclophanes 1.1.2. Isomers of Benzene 1.1.3. Naphthalene and Derivatives 1.1.4. 2,2′-Binaphthyl 1.1.5. Acenaphthylene 1.1.6. Anthracenes 1.1.7. Tetracenes, Pentacenes 1.1.8. Phenanthrene 1.1.9. Picene, Peropyrene 1.1.10. Pentafulvenes, Heptafulvenes 1.1.11. Cyclopentadienones 1.1.12. 2-Indenes 1.1.13. Semibullvalenes, Triquinacene 1.1.14. Annulenes 1.1.15. Bridged Annulenes and Propellanes 1.1.16. Pentalenes, Azulenes, Cyclopenta[cd]azulenes, Cyclopenta[ef]heptalene (Aceheptylene) 1.1.17. Cyclopentadienyl-Metal Complexes 1.2. Addition to Heteroarenes and Related Cyclic Systems 1.2.1. 1,2,4-Triazines, 1,2,3,4,5-Tetrazines 1.2.2. 2-Pyridones 1.2.3. Pyrroles, Indolizines, (Indoles), Stannoles 1.2.4. 2- and 4-Pyrones 1.2.5. Chromenes, Coumarins 1.2.6. 6-Oxo-6H-1,3-oxazines 1.2.7. Furans 1.2.8. 1,2-Oxazoles, 1,3-Oxazoles, 1,3-Thiazoles, Benzazoles 1.2.9. Thiophene and Derivatives 1.2.10. 1,4-Dithiin 1,1-Dioxides 1.2.11. Azepines 1.2.12. 1.4-Diazepine Derivatives 1.2.13. Quinolines, Isoquinolines, Acridizinium Salts 1.2.14. [1,2,4]Triazolo-, Tetrazolo-, and Imidazopyridines 1.2.15. Phosphorins, 2-Benzophosphorins, Silabenzenes 1.2.16. Heterocyclic Thioxo Compounds 1.2.17. Mesoionic Heteroarenes