Challenges and Opportunities in the Post‐Synthetic Modification of Interlocked Molecules

Abstract

Scheme 14. Stopper exchange of a[ 2]rotaxanec ontaining acinnamyl ester through aT suji-Trost allylation. Scheme 15. Synthesis of aruthenium-containing [2]rotaxaneb uilding block and af urther allyl insertion.

A Chiral Interlocking Auxiliary Strategy for the Synthesis of Mechanically Planar Chiral Rotaxanes

“…By employing a cross-coupling reaction as the stoppering step, late-stage diversification of a single rotaxane building block was also achieved. 32 Using our approach, we also demonstrated an unusual property of combining molecular motion and mechanical chirality, namely the potential to synthesize both hands of an MPC target using the same starting materials by controlling which end of the axle the macrocycle is effectively threaded on from.…”

Precision synthesis of linear oligorotaxanes and polyrotaxanes achieving well-defined positions and numbers of cyclic components on the axle

“…60 In addition, the binding target of macrocycle 8 was the sterically defined benzylalkylammonium cation of 4, while macrocycle 7 selectively recognized the dibenzylammonium unit of 5 because the corresponding assembly would provide the largest binding constant among the three cation moieties. 55 This complementary association between the axle cation units and macrocycles 6-8 selectively afforded hetero [6]rotaxane 9.…”

“…Furthermore, sequential control using multiple types of stations on the axle molecule allows the formation of sequence-defined oligorotaxanes with multiple macrocyclic components. [55][56][57][58] For example, Qu et al combined axles 4 and 5 to synthesize a hetero [6]rotaxane containing three types of macrocycles (6)(7)(8) in a defined sequence on the combined axle molecule (Fig. 3).…”

“…39,71 The deprotection of the resultant rotaxane yielded a terminal alkyne, which could be utilized as the reaction site for subsequent extension of the rotaxane. The iterative process allowed [n]rotaxanes to be converted to [n + 1]rotaxanes, up to [6]rotaxane 14, in excellent yields (490% for each process). Moreover, changing the macrocycle introduced in each step afforded hetero [4]rotaxanes (15) containing different cyclic molecules in a well-defined sequence on the axle (Fig.…”

A Chiral Interlocking Auxiliary Strategy for the Synthesis of Mechanically Planar Chiral Rotaxanes

“…Finally, we extended our synthesis of impossible MPC rotaxanes by demonstrating the use of our Pd 0mediated cross-coupling stoppering approach in the late-stage diversification of a common building block. 28 Rotaxane (S,Smp)-17 was synthesized from the corresponding alkyne block by reaction with macrocycle 2 and azide (S)-1 in excellent yield and subjected to a Sonagashira cross-coupling with phenyl acetylene to give conjugated rotaxane (Smp)-18, Suzuki cross-coupling with PhB(OH)2 to produce (Smp)-19, and Suzuki cross-coupling with pyrene-boronic acid to give rotaxane (Smp)-20 all in good yield and enantiopurity (≥94% ee in all cases).…”