C−C Bond-Forming Click Synthesis of Rotaxanes Exploiting Nitrile N-Oxide

Abstract

A click end-capping reaction exploiting nitrile N-oxide to rotaxane was described with emphasis of productivity of the protocol via stable C-C bond formation. Establishment of a pH-driven molecular shuttling system was also demonstrated by practical neutralization of the sec-ammonium group of the rotaxane axle with potassium hydroxide.

Reactions under the Click Chemistry Philosophy Employed in Supramolecular and Mechanostereochemical Systems

“…The group of Takata [44] has described the synthesis of a series of rotaxanes (Scheme 16) using the threading-followed-by-stoppering approach by relying upon templation between a crown ether ring component and a À CH 2 NH 2 + CH 2 À recognition site. In the optimized case, the cycloaddition leading to the final [2]rotaxane 21 + was achieved in 98 % yield after heating at reflux in CH 2 Cl 2 for 2 h.…”

Polymer architectures assisted by dynamic covalent bonds: synthesis and properties of boronate-functionalized polyrotaxane and graft polyrotaxane

“…For 8 (Figure 1c), a signal originating from N-benzyl protons around the ammonium moiety appears as a broad peak because of geminal coupling, strongly supporting the formation of rotaxane in accordance with the literatures. 47,48 In addition, the observed methyl signal supports the formation of boron pinacolate of 8. The other signals are consistent with the structure of 8.…”

Fluorescent poly(boron enaminoketonate)s: synthesis via the direct modification of polyisoxazoles obtained from the click polymerization of a homoditopic nitrile N-oxide and diynes

“…Building upon our previous study, [24][25][26][27][28][29][30][31][32][33][34][35][36] we selected bis(2-alcoxy-naphthalene nitrile N-oxide) as a skeleton, speculating that it should serve well as a framework for a sufficiently-stabilized homoditopic nitrile N-oxide. Synthesis of the homoditopic nitrile N-oxide 1 was accomplished in 58% overall yield via a three-step reaction (Scheme 1, m.p.…”

“…applications not only to polymeric materials but also supramolecular chemistry because we have previously reported effective synthesis of rotaxane and polyrotaxane exploiting a cycloaddition of stable nitrile N-oxide. 16,27,30,33,36 The study of stimuli-responsive fluorescent switching system using BEK-containing supramolecular skeleton will be important for future. …”