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In polymer chemistry, ring-opening polymerization (ROP) is a form of chain-growth polymerization in which the terminus of a polymer chain attacks cyclic monomers to form a longer polymer (see figure). The reactive center can be radical, anionic or cationic. Ring-opening of cyclic monomers is often driven by the relief of bond-angle strain.
A scheme showing ring expansion by exocyclic bond migration (A) and ring opening of a bicyclic molecule (B). Ring expansions can allow access to larger systems that can be difficult to synthesize otherwise. [6] Rings can be expanded by attack of the ring onto an outside group already appended to the ring (a migration/insertion), opening of a ...
The Enders SAMP/RAMP hydrazone alkylation begins with the synthesis of the hydrazone from a N,N-dialkylhydrazine and a ketone or aldehyde [14]. The hydrazone is then deprotonated on the α-carbon position by a strong base, such as lithium diisopropylamide (LDA), leading to the formation of a resonance stabilized anion - an azaenolate.
The mechanism of homogeneous ring-opening metathesis polymerization is well-studied. It is similar to any olefin metathesis reaction. Initiation occurs by forming an open coordination site on the catalyst. Propagation happens via a metallacycle intermediate formed after a 2+2 cycloaddition. When using a G3 catalyst, 2+2 cycloaddition is the ...
Impurities are likely to consist of either pyrrolidine or alpha-dibrominated alkylphenones—respectively, from either excess pyrrolidine or incomplete amination during synthesis. These impurities likely account for its discoloration and fishy (pyrrolidine) or bromine -like odor, which worsens upon exposure to air, moisture, or bases.
Similarly, S. W. Baldwin and T. J. Doll examined a modification of the Hofmann–Löffler–Freytag reaction during their studies towards the synthesis of the alkaloid gelsemicine 41. The formation of the pyrrolidine ring of 40 was accomplished by irradiation of N-chloroamide 39. [19]
1-(2-Phenylethyl)pyrrolidine (PEP) is a chemical compound. It is an analogue of 2-phenylethylamine where the amine has been replaced by a pyrrolidine ring . The β- keto derivative is phenacylpyrrolidine and the α- methyl and β-keto (i.e., cathinone ) derivative is α-pyrrolidinopropiophenone (α-PPP).
The polar reaction, N-cyclopentenyl pyrrolidine nucleophilic addition to the diazo compound, proceeds 1,500 times faster in polar DMSO than in non-polar decalin. On the other hand, a close analog of this reaction, N-cyclo hex enyl pyrrolidine 1,3-dipolar cycloaddition to dimethyl diazomalonate, is sped up only 41-fold in DMSO relative to decalin.