1132648-10-2Relevant articles and documents
Dynamic covalent chemistry of the Nicholas ether-exchange reaction
Kihara, Nobuhiro,Kidoba, Kazuyuki
, p. 1313 - 1316 (2009)
The Nicholas ether-exchange reaction was found to be reversible and can be used to synthesize complex molecules in dynamic covalent chemistry (DCC). The Nicholas ether-exchange reaction is used to prepare 20-Crown-6 ether in the presence of potassium salt
Alkynyl crown ethers as a scaffold for hyperconjugative assistance in noncatalyzed azide-alkyne click reactions: Ion sensing through enhanced transition-state stabilization
Gold, Brian,Batsomboon, Paratchata,Dudley, Gregory B.,Alabugin, Igor V.
, p. 6221 - 6232 (2014)
Our recent work has provided an alternative strategy for acceleration of azide/alkyne cycloadditions via selective transition state (TS) stabilization. Optimization of hyperconjugative assistance, provided by the antiperiplanar arrangement of propargylic -acceptors relative to the forming bonds, is predicted to relieve strain in cyclooctynes while providing large acceleration to the cycloaddition. The present work investigates this strategy in alkynyl crown ethers, where propargylic C-O bonds contained within the macrocycle are constrained close to proper alignment for hyperconjugative assistance. Preorganization of -acceptors into the optimal arrangement for hyperconjugative interactions may alleviate a portion of the entropic penalty for reaching the TS. Optimal alignment can be reinforced, and transition-state stabilization can be further amplified by binding positively charged ions to the crown ether core, highlighting the potential for applications in ion sensing.
