Molecular riveting: high yield preparation of a [3]-rotaxane

Recent Advances in the Synthesis of Ammonium-Based Rotaxanes

“…Their strategy consists in the formation of a disulfide by oxidizing a pseudorotaxane bearing a thiol (-SH) on the rod with iodine (Scheme 4). This leads in very good yield (84%) to symmetrical [3]rotaxanes, in which the two crown ethers lie close one to each other [20]. The most interesting feature of the disulfide formation is the reversibility of that bond.…”

“…Busch et al proposed in the late 90's a strategy to prepare a reversible rotaxane (rotaxane/ pseudorotaxane equilibrium) [20]. Their strategy consists in the formation of a disulfide by oxidizing a pseudorotaxane bearing a thiol (-SH) on the rod with iodine (Scheme 4).…”

An Introduction to the Mechanical Bond

“…See Chapter 3 for a review of MIM synthesis under thermodynamic control. Seminal examples 129,202,[309][310][311][312][313][314] of elegant thermodynamically controlled protocols for making mechanical bonds are illustrated in Figure 1.32. They include (in order of appearance) (i) slippage 309 (Section 3.1), which involves the passage of a ring over a size-complementary stopper that is sufficiently bulky to prevent deslipping, (ii) olefin metathesis 310 (Section 3.4), which involves a catalysttypically Grubbs' Ru alkylidene catalysts-scrambling the constituents of double bonds, (iii) disulfide exchange (Section 3.5.1), which involves the oxidative coupling of thiols and reductive cleavage of disulfides, (iv) kinetically labile metal-ligand bonds (Section 3.2)-a revolution led by Makoto Fujita,202 (v) reversible nucleophilic substitutions (Section 3.5.2), such competing S N 2 processes 312 in dynamic equilibrium, (vi) imine bonds 129,315 (Section 3.3.1) whose reversible nature facilitates the self-assembly of MIMs, (vii) boronic esters 313 (Section 3.3.3) formed reversibly from boronic acids and diols, and (viii) self-assembled monolayers 314 (SAMs) (Section 3.6).…”

Templated Synthesis of Interlocked Molecules

“…Extensive mechanistic studies on thiols and disulfides by Whitesides [203] has shown that disulfide exchange takes place efficiently under mild conditions in the presence of a catalytic amount of a thiol and that disulfides are stable toward many different functional groups.Although disulfide linkages have been employed in the synthesis of both catenanes [204] and rotaxanes 5 [205], this potentially reversible covalent bond was employed for the first time to construct an interlocked molecule under thermodynamic control in early 2000 by the Takata group [206][207].A symmetrical dumbbell-shaped compound 75-H 2 ·2PF 6 possessing two secondary dialkylammonium ion centers in addition to a centrally located disulfide linkage was synthesized. In the knowledge that DB24C8 can bind secondary dialkylammonium ions within its macroring, two equivalents of this crown ether were added (Scheme 13) to a solution of 75-H 2 ·2PF 6 in CD 3 CN.…”