Über 9.10‐Dihydro‐anthracen‐Derivate mit Heterobrückenatomen

Abstract

Dehydrobenzol als reaktionsfreudiges Dienophil laBt sich bei geeigneten Partnern zur Synthese von Dihydroanthracen-Derivaten mit 0, S oder N als Briikkenatomen in 9.10-Position verwenden. Nach diesem Verfahren wurden die 0-Verbindung 111, ihr S-Analogon sowie die N-Verbindungen VlII und XI11 prapariert, deren Strukturen und Eigenschaften beschrieben werden. Besonderes Interesse verdient die Verbindung VIII mit CH3. N-Briicke, da sich die zugehorige quartare Base XI in pseudomonomolekularer Reaktion zu den cis-transisomeren Aminoalkoholen XI1 umlagert. Das ausgepragt dienophile Verhalten von Dehydrobenzol lud dazu ein, es mit Verbindungen vom Typ I mit dem Ziele umzusetzen, eine neue Verbindungsklasse I1 zuganglich zu machen, in der die beiden meso-Kohlenstoffatome des Anthracens durch 0-, S-oder N-Atome verbriickt sind. Wie aus dem Folgenden hervorgeht, bereiteten die Synthesen solcher Verbindungen keine Schwierigkeiten. I Dehydrobenzol wurde nach der ublichen Arbeitstechnikz) aus o-Fluor-brombenzol und Magnesium in Tetrahydrofuran erzeugt. Seine Einwirkung auf 2.5-Diphenyl-3.4-benzo-furan lieferte 9.10-Diphenyl-9.ZO-oxido-dihydroanthracen (111) vom Schmp. 188-188.5'. Die Struktur I11 folgt aus der glatt verlaufenden Reduktion zum 9.10-Diphenyl-anthracen mit Zink in Eisessig.

Reductive Aromatization/Dearomatization and Elimination Reactions to Access Conjugated Polycyclic Hydrocarbons, Heteroacenes, and Cumulenes

“…Wittig and Pohmer first demonstrated in 1955 that the 1,4‐epoxinaphthalene from the Diels–Alder cyclization of benzyne and furan could be transformed to 1‐naphthol via reaction with MeOH and HCl . They subsequently demonstrated that anthracene 112 a could be synthesized by heating the corresponding endoxide ( 113 a ) with zinc dust in acetic acid at reflux (Scheme ) . Rickborn and Bhatt independently applied the same methodology to produce a variety of substituted CPHs (e.g., 112 b , c ), while Pascal and co‐workers have used it to produce highly twisted CPHs such as decaphenylanthracene and dibenzo[ a‐c ]naphthacene 114 , a tetracene analogue with an end‐to‐end twist of 105°.…”

“…[168g] They subsequently demonstrated that anthracene 112a could be synthesized by heating the corresponding endoxide (113a)w ith zinc dust in acetic acid at reflux (Scheme 46). [169] Rickborn and Bhatt independently applied the same methodology to produce av ariety of substituted CPHs (e.g., 112b,c), [170] while Pascal and co-workersh ave used it to produce highly twisted CPHs such as decaphenylanthracene [171] and dibenzo[a-c]naphthacene 114, [172] at etracene analogue with an end-to-end twist of 1058.…”

Mycophenolic Acid: Biogenesis, Compound Isolation, Biological Activity, and Historical Advances in Total Synthesis

“…Cycloaddition transformations is one of the reaction which has been explored for the synthesis of aromatic system in a one pot manner . For the invention of new synthetic natural product analogues having the heteroatom in the cyclic system was also an important structural aspect for optimizing biological properties.…”

Observations related to the preparation of 2-phenyliodoniobenzoate

“…6-Nitro-l ,2,3,4-tetraphenylnaphthalene was prepared in 86% yield from 2,3,4,5-tetraphenylcyclopentadienone and 5-nitro-2phenyliodoniobenzoate by a method analogous to that of Fieser.7 Recrystallization (chloroform-methanol) yielded yellow crystals: mp 275-277°; uv max (95% EtOH) 208 µ (e 53,500), 231 (38,000), 279 (29,500); ir (Nujol) 1522 and 1339 cm'1 (NOa); nmr 1.35 (d of d, 1, J = 0.5, 2.5 Hz), 1.87 (d of d, 1, J = 2.5, 8.5 Hz), 2.22 (d of d, 1, J = 0.5, 8.5 Hz), 2.75 (m, 10), 3.13 (m, 10); mass spectrum m/e 477 (30), 447 (7), 78 (100), 77 (16), 52 (17), 51 (16), 50 (13).…”

“…After 3 min, excess anthracene was removed by addition of maleic anhydride (0.49 g, 5 mmol), refluxing for 5 min, and then adding ethanolic potassium hydroxide. The crystals which appeared upon cooling in an ice bath were filtered, washed with aqueous methanol, and dried to give 2-nitrotriptycene: 43% yield; mp 277-279°( methylene chloride-methanol) (lit.8 mp 270-271°); ir (Nujol) 1517 and 1340 cm.-1 (N02); nmr r 1.80 (d, 1, J = 2.5 Hz), 2.08 (d of d, 1, J = 2.5, 8.5 Hz), 2.57 (m, 5), 2.92 (m, 4), 4.48 (s, 2); mass spectrum m/e 299 (100), 282 (18), 254 (11), 253 (60), 252 (100), 251 (17), 250 (27), 127 (12), 126 (24), 124 (16), 113 (13).…”