High‐Yield Synthesis of [2] Catenanes by Intramolecular Ring‐Closing Metathesis

Abstract

COMMUNICATIONS ethane (33.3 mol%) and nitrogen, with or without any additive (higher alkanes or olefins), as the feed at a space velocity of 6100+_ 100 cm3 g-' h-* w' ith a squarepulse technique descrlbed earlier [21]. The space velocity was measured at 0 "C and 1 atm. Conversion X in %, S,, in %, and yield of arene based on ethane conversion ( YArlCIHs) in %) were determined as follows: X = [{(wt% of reactant in the feed hydrocarbons) -(wt% of reactant in the product hydrocarbons)}/(wt% of reactant in the feed hydrocarbons)] x 100; S,, = [(wt% of arenes in the hydrocarbon products)/{l00 -wt% of reactant(s) in the hydrocarbon products]] x 100; YAr,Cz",, = (XS*,)/~OO.Angew (%en?. Int. G I EngI. 1997, 36, N o . 12 :(; VCH Ve~lrigsgesrilrcbfi~ mhH, 0-69451 Wi+diein?. I997 0570-OH33!Y7~3612-1309 S 17.56 +.SO 0 Experimental Section General procedure for ruthenium benzylidene catalyzed RCM : Under exclusion from air and moisture, 1 (5 mol%) in CH,CI, was added to a 0.01 M solution of the diolefin (typically 200 to 900 mg) in CH,CI,. After the mixture was stirred for 6 h at room temperature, additional catalyst (5 mol%) was added, and stirring continued for 6 h. The solvent was then removed under reduced pressure, and the crude reaction mixture purified by repeated column chromatography (silica gel, CH,CI,/ MeOH 9614 viv) to yield the [2]catenates as burgundy solids. All compounds were characterized by NMR spectrscopy, FAB-MS, and elemental analysis.

Ring closing metathesis employing organometallic substrates and the templated synthesis of macrocycles

“…283419 (27). Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44 1223 3360333 or e-mail: deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).…”

“…A pioneering study by Sauvage and Grubbs detailed the generation of catenanes using bis(olefin) appended 9,10-phenanthroline copper complexes via ring-closing metathesis (RCM) and subsequent demetalation, Fig. 2 [27,28]. A molecular knot of similar composition was also reported [29].…”

Dynamic donor–acceptor [2]catenanes

“…Although the stabilizing noncovalent interactions associated with the matching recognition sites are used routinely in a templating fashion to preorganize precursors in the kinetically controlled preparation of [2]catenanes, they have been used very rarely (11,12) as the thermodynamic driving force in their template-directed synthesis under equilibrium control. The vast majority of preparative strategies to access catenanes, and organic compounds in general, still relies on irreversible, kinetically controlled reactions.…”

“…The initial nucleophilic attack of iodide ion, which opens up the -acceptor ring, is followed by complexation to the -donor ring and the subsequent catenation of the -donor ring by the -acceptor ring [2]catenane. The reaction is general in scope and proceeds in high yields, without giving rise to side-products.mechanically interlocked molecules ͉ nucleophilic catalysis ͉ self-assembly T opologically nontrivial molecules dubbed catenanes (1) contain two or more mutually interlocked, inseparable rings, arranged mechanically like the links in a chain.[2]Catenanes with several complementary recognition sites expressed as matching pairs between their two rings can be rendered bistable (2) or multistable (3) and hence endowed with switching properties (4), paving the way for molecular device applications, straddling diversity from unidirectional motors (5, 6) through reconfigurable switches (7,8) to components of electronic displays (9, 10).Although the stabilizing noncovalent interactions associated with the matching recognition sites are used routinely in a templating fashion to preorganize precursors in the kinetically controlled preparation of [2]catenanes, they have been used very rarely (11,12) as the thermodynamic driving force in their template-directed synthesis under equilibrium control. The vast majority of preparative strategies to access catenanes, and organic compounds in general, still relies on irreversible, kinetically controlled reactions.…”

Templated Synthesis of Interlocked Molecules

“…In 1998, the Sanders group [149] explored the use of dynamic covalent bond formation for synthesizing neutral p-associated [2]catenanes by ring-closing metathesis (RCM) [150][151][152][153][154][155][156][157][158][159][160]. The mechanically interlocked structure was achieved using the electronic complementarity of p-electron-deficient aromatic diimides substituted with olefin terminated alkyl chains and the p-electron-rich dinaphtho [38]crown-10 (DN38C10) in the presence of the catalyst 4.…”