Controlled Metathetic Depolymerization of Natural Rubber in Ionic Liquids: From Waste Tires to Telechelic Polyisoprene Oligomers

A controlled degradation process enabling Natural Rubber (NR) depolymerization and using the olefin metathesis reaction in ionic liquid medium is reported. Using trihexyl-(tetradecyl)­phosphonium chloride (Cyphos101) and N,N-dioctylimidazolium bromide (C₈C₈ImBr), low-dispersity telechelic polymers are produced. With N,N-dioctylimidazolium bromide (C₈C₈ImBr), the degradation process could be performed for five consecutive cycles with excellent control. This degradation process was successfully applied to waste tires

Reaction of Glyconitriles with Organometallic Reagents: Access to Acyl β‑<i>C</i>‑Glycosides

A new strategy for the synthesis of acyl β-<i>C</i>-glycosides is described. The reactivity of glyconitriles toward organometallic reagents such as organomagnesium or organolithium derivatives was studied, affording acyl β-<i>C</i>-glycosides in moderate to good yields. In this study, glycal formation was efficiently prevented by deprotonating the hydroxyl group in position 2 of the glyconitriles during the process

<i>ortho</i>-Lithium/Magnesium Carboxylate-Driven Aromatic Nucleophilic Substitution Reactions on Unprotected Naphthoic Acids

Substitution of an <i>ortho</i>-fluoro or methoxy group in 1- and 2-naphthoic acids furnishing substituted naphthoic acids occurs in good to excellent yields upon reaction with alkyl/vinyl/aryl organolithium and Grignard reagents, in the absence of a metal catalyst without the need to protect the carboxyl (CO₂H) group. This novel nucleophilic aromatic substitution is presumed to proceed via a precoordination of the organometallic with the substrate, followed by an addition/elimination