0000000000214755
AUTHOR
Bernd Rose
Dehydrotriphenylene zum Aufbau gewinkelter molekularer Bandstrukturen
Dehydrotriphenylenes for the Generation of Bent Molecular Ribbons The synthetic sequences 1 11 and 17 23a lead to highly reactive mono- and bisdienophiles whose cycloaddition processes with in situ generated isobenzofuran 13 were studied: 11 + 13 15 and 23a + 2×13 24a.
Synthesis and Stereochemistry of Diepoxynaphthacenes and Tetraepoxyheptacenes
Cycloaddition reactions of 1,4-dihydro-1,4-epoxynaphthalenes (2) and benzo[c]furans (4), generated in situ from the tetracyclone adducts of 2, yield the diepoxynaphthacenes 5 (Schemes 1, 2). Out of 4 possible stereoisomers an exo-exo and an exo-endo geometry (A and C in Scheme 3) can be realized. The ratio A:C varies from pure A to pure C depending on the substituents of 2 and 4. Stereoisomeric heptacenes 7 can be obtained by a twofold cycloaddition of the same type (Scheme 4). Only one π bond of reactive alkynes such as cyclooctyne or acetylenedicarboxylate is capable of an addition to 4 (Schemes 5, 6).
Band-Shaped Structures by Repetitive Cycloaddition Reactions of Benzo[1,2-b:4,5-b′]bisthiete
Benzo[1,2-b:4,5-b′]bisthiete (1) undergoes stepwise thermal opening of the 4-membered rings, thereby generating two highly reactive 8π systems (Scheme 1). In the presence of 1,4-dihydro-1,4-epoxynaphthalenes 2, the dithiaheptacene derivatives 3 are formed, dehydration of which leads to the compounds 4 and 5 (Scheme 2). Repetitive cycloaddition reactions of 1 with the twofold 2π component 11 (Scheme 3) yield the oligomers 15 with statistically bent (and possibly cyclic) structures (Schemes 4 and 5). While 15 and the related oligomers 14 are freely soluble in many organic solvents, the dehydrated systems 16 (Scheme 6) are totally insoluble.
ChemInform Abstract: Synthesis of a Tetraazido-Substituted 2-Tetrazene from 1,5- Cyclooctadiene and Iodine Azide.
In contrast to the addition of iodine azide to cyclooctene (1) or 1,3-cyclooctadiene (5), its reaction with 1,5-cyclooctadiene (12) leads mainly to the surprisingly stable tetraazido-substituted 2-tetrazene 14 The structure of this was established by 15N-NMR studies and an X-ray structural analysis. Treatment of 14 with hydrochloric acid yields the diazido-substituted 9-azabicyclo[3.3.1]nonane 20.
Synthesis of a Tetraazido-Substituted 2-Tetrazene from 1,5-Cyclooctadiene and Iodine Azide
In contrast to the addition of iodine azide to cyclooctene (1) or 1,3-cyclooctadiene (5), its reaction with 1,5-cyclooctadiene (12) leads mainly to the surprisingly stable tetraazido-substituted 2-tetrazene 14 The structure of this was established by 15N-NMR studies and an X-ray structural analysis. Treatment of 14 with hydrochloric acid yields the diazido-substituted 9-azabicyclo[3.3.1]nonane 20.
Herstellung von 1,5‐Cyclooctadiin und 1,3,5,7‐Cyclooctatetraen aus 1,5‐Cyclooctadien
Preparation of 1,5-Cyclooctadiyne and 1,3,5,7-Cyclooctatetraene from 1,5-Cyclooctadiene Bromination of 1,5-cyclooctadiene (1) and stepwise dehydro-bromination first with KOtBu and then with KOtBu/18-crown-6 yields 1,5-cyclooctadiyne (5). A prolonged interaction of the base causes a complete transformation to cyclooc-tatetraene (6). Diyne 5 and even more the intermediate enyne 4 are highly reactive dienophiles. The cycloadducts 10–14 formed with 1,3-cyclohexadiene, carbon disulfide, and tetraphenylcyclopentadienone were isolated and characterized. Treatment of 5 with titanium tetrachloride induces a vigorous polymerization.