En Route to a Molecular Sheaf: Active Metal Template Synthesis of a [3]Rotaxane with Two Axles Threaded through One Ring

Abstract

We report that a 2,2':6',2″-terpyridylmacrocycle-Ni complex can efficiently mediate the threading of two alkyl chains with bulky end groups in an active metal template sp(3)-carbon-to-sp(3)-carbon homocoupling reaction, resulting in a rare example of a doubly threaded [3]rotaxane in up to 51% yield. The unusual architecture is confirmed by X-ray crystallography (the first time that a one-ring-two-thread [3]rotaxane has been characterized in the solid state) and is found to be stable with respect to dethreading despite the large ring size of the macrocycle. Through such active template reactions, in principle, a macrocycle should be able to assemble as many axles in its cavity as the size of the ring and the stoppers will allow. A general method for threading multiple axles through a macrocycle adds significantly to the tools available for the synthesis of different types of rotaxane architectures.

Complex lasso: new entangled motifs in proteins

“…On the other hand, there is no exact analogs of the L 2 , L 3 , L 6 , LS and LL lasso types. Most similar, doubly-threaded [3]rotaxane are still the exotics of chemical topology3839404142 with only one, recent example of triply-threaded [4]rotaxane known to us43. Properties and use of such compounds are still poorly understood, and hard to correlate with lasso proteins.…”

An Introduction to the Mechanical Bond

“…A similar concept involves two dumbbells encircled by a single ring-an architecture (Figure 1.28e, Section 4.2.1.2) first created by Anderson. 305 Sauvage 306 and Leigh 307 have also created examples of these doubly threaded architectures, the latter case, which was nicknamed a 'molecular sheaf', includes a crystal structure (Figure 1.29c) 265 Solvent molecules, counterions, and protons are omitted for the sake of clarity. molecular sheaf (Figure 1.29h) comprising two dumbbells, each encircled by two inorganic rings, has also been described by Leigh and Winpenny.…”

“…314 See Chapter 3. C-S couplings, 332 Cadiot-Chodkiewicz alkyne heterocouplings, 335 as well as Pd-and Ni-mediated homocouplings, 336,337 Ni-catalyzed sp 3 -sp 3 homocoupling of unactivated alkyl bromides, 307,338 oxidative Heck cross-couplings, 339 Michael additions, 340 Diels-Alder reactions, 341 and Goldberg amidations. 342 See Section 2.4 for a review of active template strategies.…”

Synthesis of [3]Rotaxanes by the Combination of Copper-Mediated Coupling Reaction and Metal-Template Approach

“…The combined organic layer was washed with water, dried over Na 2 SO 4 , and concentrated. The residue was purified by silica gel column chromatography using CH 2 Cl 2 and GPC using CHCl 3 to afford 15d (70 mg, 0.014 mmol) in 70% yield as a pale yellow amorphous solid; 1 H NMR (500 MHz, CDCl 3 ) δ 8.35 m),8.15 (2H,d,J = 8.5 Hz),8.08 (2H,d,J = 8.0 Hz),m),7.79 (2H,d,J = 8.5 Hz),7.68 (2H,s),7.60 (2H,s),m),7.34 (12H,d,J = 8.5 Hz),m), 7.14−7.07 (9H, m), 6.96 (1H, s), 6.83 (4H,d,J = 8.5 Hz),m),5.13 (4H,s) 7, 159.9, 159.7, 159.5, 158.2, 156.2, 147.03, 146.99, 146.5, 146.4, 146.2, 146.0, 143.2, 138.4, 138.2, 138.1, 136.6, 136.5, 133.9, 132.5, 132.2, 129.6, 129.50, 129.45, 129.4, 128.9, 127.6, 127.4, 127.2, 127.1, 126.8, 126.7, 126.2, 125.8, 125.5, 123.9, 121.2, 119.2, 115.0, 114.7, 114.3, 113.3, 107.5, 101.6, 82.5, 74.4, 68.3, 67.83, 67.77, 62.4, 56.0, 55.9, 49.9, 44.2, 40.5, 40.3, 34.4, 30.5, 30.1, 29.9, 29.8, 29.73, 29.70, 29.64, 29.57, 29.50, 29.40, 29.37, 29.1, 26.9, 26.4, 26.1, 26.0, 25.9, 25.7, 25.6;IR (ATR) 3029, 2921, 2849, 1907, 1602, 1493, 1466, 1446, 1244, 1171, 1004 [3]Rotaxane (15e). To a solution of 2 (7.0 mg, 0.019 mmol) in dry CH 3 CN (1.1 mL) was added a solution of [2]rotaxane 7b (55 mg, 0.019 mmol) in dry CH 2 Cl 2 (2.3 mL), and the mixture was stirred at room temperature for 3 h. To the reaction mixture was added a solution of 16 (18 mg, 0.019 mmol) in dry CH 2 Cl 2 (2.3 mL).…”