Post‐Synthetic Macrocyclization of Rotaxane Building Blocks

Abstract

Although not often encountered, cyclic interlocked molecules are appealing molecular targets because of their restrained tridimensional structure which is related to both the cyclic and interlocked shapes. Interlocked molecules such as rotaxane building blocks may be good candidates for post‐synthetic intramolecular cyclization if the preservation of the mechanical bond ensures the interlocked architecture throughout the reaction. This is obviously the case if the modification does not involve the cleavage of either the macrocycle's main chain or the encircled part of the axle. However, among the post‐synthetic reactions, the chemical linkage between two reactive sites belonging to embedded elements of rotaxanes still consists of an underexploited route to interlocked cyclic molecules. This Review lists the rare examples of macrocyclization through chemical connection between reactive sites belonging to a surrounding macrocycle and/or an encircled axle of interlocked rotaxanes.

The Role of Dethreading Process in Pseudorotaxanes and Rotaxanes towards Advanced Applications: Recent Examples

“…As abovementioned, most of the synthetic strategies towards rotaxanated architecture pretend the formation of robust structures in which the interlocked assembly is not threatened, thus disrupting the dethreading process [31–35] . In stark contrast, certain design difficulties arise when systems in which a dethreading process can be induced by the application of external stimuli are required.…”

Ring‐to‐Thread Chirality Transfer in [2]Rotaxanes for the Synthesis of Enantioenriched Lactams

“…Diastereoselective functionalization of a [2]rotaxane where the chiral macrocycle induces: A) a marginally diastereoselective endcapping reaction of the thread in pseudorotaxane 1; [34] B) a selective oxidation to afford a diastereomeric mixture of rotaxanes 4. [35] R = 3,5-t Bu 2 C 6 H 3 chiral influence of the ring, with axially chiral binaphtyl units, in a [2]rotaxane [42,43] In this manuscript we disclose our results on approaching a similar strategy by using another type of stereogenic inductor, point chirality (only a single chiral carbon atom! ), placed at the macrocycle of a [2]rotaxane, and a different diastereoselective transformation occurring at the thread.…”

Ring‐to‐Thread Chirality Transfer in [2]Rotaxanes for the Synthesis of Enantioenriched Lactams

“…The reactions shown in Scheme 1 are probably the only two examples known of diastereoselective post‐synthetic modification of the achiral thread carried out under the chiral influence of the ring, with axially chiral binaphtyl units, in a [2]rotaxane [42, 43] In this manuscript we disclose our results on approaching a similar strategy by using another type of stereogenic inductor, point chirality ( only a single chiral carbon atom ! ), placed at the macrocycle of a [2]rotaxane, and a different diastereoselective transformation occurring at the thread.…”