Structural Characterization of a Cyclohexamericmeta-Phenyleneethynylene Made by Alkyne Metathesis with In Situ Catalysts

Abstract

New hexameric cyclophenyleneethynylenes (CPEs, 1) were synthesized by alkyne metathesis of meta‐dipropynylated benzenes. Treatment of one of these CPE derivatives (R1=tert‐butyl, hexyl, dodecyl; R2=H, methyl) with [Os3(CO)10(MeCN)2] led to a decacarbonyltriosmium–CPE complex in which the planarity of the ring was significantly disrupted, as evidenced by the results of the single‐crystal X‐ray diffraction analysis.

Shape-Persistent, Nano-Sized Macrocycles

“…Bunz reported random macrocyclization through alkyne metathesis [99] of the symmetrical monomer 68 (Scheme 25). [27,28,100] The 30-membered cyclic hexamers 5cϪf were isolated from the raw mixture in yields of 0.5Ϫ6%. Finally, Oda reported the synthesis of 30-membered phenylacetylene macrocycles 5g and 5h by a strategy in which the aldehyde-functionalized precursors 69 or 70 were cyclized to provide 39a and 39b by means of a twofold McMurry-type coupling reaction (Scheme 26).…”

“…n.s. B 1 MS, NMR 5c [27,28] 6% 30 mg C 6 m.p., MS, NMR, IR, UV, EA, X-ray 5d [27,28] 1.2% 4.8 mg C 6 MS, NMR 5f [27,28] 0.5% 2.3 mg C 6 MS, NMR 5g [29] R MS, NMR, IR 5h [29] R MS, NMR, UV, IR, X-ray 6a [ [32] 16% n.s. B 2 MS, 1 H NMR 9a [33] 14% 209 mg B 2 GPC, MS, 1H NMR, EA 9b [33] 5% 79 mg B 4 GPC, MS, 1H NMR, EA 10a [34] 54% 220 mg B [c] 2 MS, NMR, UV, EA 10b [34] 32% 90mg D 2 UV, (EA), charact.…”

“…Transition metal induced homo-and cross-coupling reactions therefore play the key role in their synthesis. The following six reaction types were applied for the 79 cycles, the numbers in parentheses describing the total number of cases prepared according to the respective method: aryl/aryl (4), aryl/alkynyl (32), and alkynyl/alkynyl couplings (27), acetylene zirconacyclopentadienation (11) (referred here to as zirconocene coupling), alkyne metathesis (3), and McMurry olefination (2). Clearly aryl/alkynyl (Sonogashira/Hagihara) [66] and alkynyl/alkynyl couplings are by far the most commonly used cyclization reactions.…”

Self-assembling subnanometer pores with unusual mass-transport properties

“…For example, arylene ethynylene macrocycles have been extensively studied for their aggregation via aromatic stacking 25 . Although tubular assembly is observed with a few structures in the solid state 26,27 , the packing of analogous macrocycles, with very small structural differences, varies significantly and in most cases, does not result in a truly tubular arrangement 25,28 .…”

Shape‐Persistent Macrocycles Based on Acetylenic Scaffolding

“…In this case, reactions are typically under thermodynamic control, providing the potential for increased selectivity in product formation. The initial examples using alkyne metathesis toward the formation of SPMs were reported by Adams, Bunz, and coworkers using the precatalyst [Mo(CO) 6 ] [27,28], but rather low yields of the desired products (4) limited general applicability (Scheme 6.2). Recent efforts by Moore and coworkers using a Mo(VI)-alkylidyne catalyst, however, have refined this process such that precipitation-driven reactions now provide moderate to excellent results (see Scheme 6.24) [29].…”