Neue helikale Kohlenwasserstoffe. VII. Verklammerte Quaterphenyl‐Kohlenwasserstoffe

Abstract

Die neuen vielgliedrigen Kohlenwasserstoffe 1 -4 werden ausgehend von 3-Ethoxycyclohexenon synthetisiert; 5 ist iiber eine Ullmann-Kupplung zuganglich. DNMR-Studien zeigen, daB mit Ausnahme von 4 konformativ weitgehend starre, helikale Geriiste vorliegen, wahrend die um ein Schwefelatom ringweiteren Cyclen 6 al l a niedrigere Ringinversionsbarrieren aufweisen. New Helical Hydrocarbons, VIII) Clamped Quaterphenyl HydrocarbonsThe new many-membered hydrocarbons 1 -4 are synthesized starting with 3-ethoxycyclohexenone; 5 is available through Ullmann-coupling. DNMR studies show that these molecular skeletons with the exception of 4 are comparatively rigid helices. The larger sulfide rings 6 a -l l a exhibit lower ring inversion barriers.Die zahlreichen Moglichkeiten, durch Verbriickung offenkettiger Oligophenyle zu helikalen Molekiilen zu gelangen'), regten uns dazu an, auch aus weniger symmetrischen Grundgeriisten helikale Verbindungen zu synthetisieren. Im AnschluR an die bisher untersuchten Quaterphenylophane 3), Q~inquephenylophane~) und Terphenylophane 'v5) beschreiben wir nun Synthese und intramolekulare Stereochemie neuer Quaterphenyl-Systeme 1 -4 und 6-10, die nicht symmetrisch verkniipfte Phenyleneinheiten enthalten, sowie 5 und 11 als neue Vertreter symmetrisch verkniipfter und verbriickter Quaterphenylophane.

Efficient Synthesis of Octaalkyloxy-o-quaterphenyls via Base-Induced Biaryl Coupling

“…IR (KBr): n = 3084, 2993,2960,2942,2906,2873,2858,2854,2836,1598,1498,1465,1452,1437,1418,1370,1311,1269,1246,1207,1189,1176,1144,1024,856,827,819,784, 763 cm Ð1 . 1 3,3''',4,4',4'',4''',5',5''-Octamethoxy-1,1',2',1'',2'',1'''-quaterphenyl (8a) To a solution of 7 (31.0 g, 87.8 mmol) in THF (300 mL) was added dropwise t-BuLi (27.4 ml, 43.9 mmol, 1.6 M solution in hexane) over 30 min at Ð78¡C. The resulting mixture was allowed to warm to r.t. over 20 h. Then 2 N HCl (100 mL) was added and the layers were separated.…”

“…IR (KBr): n = 3387, 1598,1504,1443,1418,1386,1364,1332,1274,1225,1205,1186,1166,1137,1110,1014,893,861,814, 778 cm Ð1 . 1 3,3''',4,4',4'',4''',5',5''-Octadecyloxy-1,1',2',1'',2'',1'''-quaterphenyl (8c) To a suspension of K 2 CO 3 (5.10 g, 36.8 mmol) in DMF (50 mL) were added quaterphenyl 8b (1.00 g, 2.30 mmol) and decyl bromide (4.07 g, 18.4 mmol) and the mixture was heated for 17 h at 120¡C. After cooling to r.t., the mixture was poured on ice (100 g) and the precipitate was isolated by filtration.…”

“…Všgtle for example used bridged, helical o -quaterphenyls (quaterphenylophanes) to study the dependence of the UV absorption from the twisting of the aryl rings. 1 o -Quaterphenyls were also employed in host-guest chemistry. The binding properties of EDTA analogues bearing an o -quaterphenyl central unit towards metal ions were determined by Všgtle.…”

“…4,5 The synthesis of these quaterphenyls relies mainly on the classical Ullmann reaction. 1,6 In addition Pd-catalyzed Suzuki coupling of aryl boronates, 7 Ni-catalyzed Kumada coupling of aryl Grignard reagents, 8 Cu(II)-catalyzed rearrangements of bora-aromatics, 5a oxidative coupling of metal phenolates, 9 and oxidative addition of Ni(0) complexes to biphenylene were used as well. 4b We have recently found that 3,3',4,4'-tetramethoxybiphenyl 6a (R = Me) could be prepared in 79% yield by treatment of 4-bromo-1,2-dimethoxybenzene 5a with 0.5 equivalents of butyllithium in THF at Ð78¡C (Scheme 2).…”

Synthesis and Structure of a Strained, Cyclic meta‐Quaterphenylene Acetylene

“…This work describes the synthesis, structure, and properties of constrained cycle 1 , a molecule that may be visualized as a meta ‐biphenylene‐linked diphenylacetylene or an alkyne‐linked meta ‐quaterphenyl. In this design, the alkyne unit clamps the terminal rings of the quaterphenyl system, generating strain in the arc‐shaped arylene system much like a tight string generates stress in a bow. Unlike many other strained, cyclic arylene ethynylenes, the most severe strain and distortion in molecule 1 was expected to be experienced by the aryl rings, rather than the alkyne group.…”