Enyne ring closing metathesis has been used to synthesize functional group carrying metathesis catalysts from a commercial (Ru-benzylidene) Grubbs' catalysts. The new Grubbs-type ruthenium carbene was used to synthesize living heterotelechelic ROMP polymers without any intermediate purification. Olefin metathesis with a mono substituted alkyne followed by ring closing metathesis with an allylic ether provided efficient access to new functional group carrying metathesis catalysts. Different functional benzylidene and alkylidene derivatives have been investigated in the synthesis of heterotelechelic polymers in one pot.

Higher ring-opening metathesis propagation rates of exo-norbornene derivatives over endo derivatives are well established in the literature. Here, we report for the first time that endo-isomers of oxanorbornene derivatives show...

Polycondensation polymers typically follow step growth kinetics assuming all functional groups are equally likely to react with one another. If the reaction rates with the chain end can be selectively accelerated, living polymers can be obtained. Here, we report on two chlorophosphonium iodide reagents that have been synthesized from triphenylphosphine and tri(o-methoxyphenyl)phosphine. The former activates aromatic carboxylic acids as acid chlorides in the presence of secondary aromatic amines and the latter even in the presence of primary aromatic amines. These reagents allow p-aminobenzoic acid derivatives to form solution stable activated monomers that polymerize in a living fashion in the presence of amine initiators. Other aryl amino acids and even dimers of aryl amino acids can be polymerized in a living fashion when slowly added to the phosphonium salt in the presence of an amine initiator. Diblock copolymers as well as a triblock terpolymer of aryl amino acids could be prepared even in the presence of electrophilic functional groups. preventing classical step-growth kinetics. The polymers obtained by this elegant method showed narrow dispersity and the possibility to form block copolymers. Poly(aromatic amides) are amongst the best investigated polymers in this context. However, low temperatures, the use of strong bases and several known side reactions 14 limit this technique as far as the average molar mass of the polymers is concerned (Mn=22 kDa). 15 As strong nucleophiles are required throughout the polymerization, the method is limited to monomers devoid of electrophilic functional groups. In particular, this technique could not yet be applied to the growing field of aromatic amide foldamers which aims at mimicking the function of biological macromolecules with similarly sized synthetic oligo and polyamides.

Terminal alkynes display high reactivity toward Ru-carbene metathesis catalysts. However, the formation of a less reactive bulky carbene hinders their homopolymerization. Simultaneously, the higher reactivity of alkynes does not allow efficient cross propagation with sterically less-hindered cycloalkene monomers, resulting in inefficient copolymerization. Nonetheless, terminal alkynes undergo rapid cross-metathesis with vinyl ethers. Therefore, an efficient cross propagation can be achieved with terminal alkynes and cyclic enol ether monomers. Here, we show that terminal alkyne derivatives can be copolymerized in an alternating fashion with 2,3-dihydrofuran using Grubbs’ third generation catalyst (G3). A linear relationship of the number-average molecular weight versus monomer to initiator ratio and block copolymer synthesis confirmed a controlled copolymerization. The SEC and NMR analyses of the synthesized copolymers confirmed the excellent control over molecular weight and exclusive alternating nature of the copolymer. The regioselective chain transfer of G3 to vinyl ether and the high reactivity of the Fischer-type Ru carbene toward terminal alkynes was also exploited for polymer conjugation. Finally, the presence of an acid labile backbone functionality in the synthesized alternating copolymers allowed complete degradation of the copolymer within a short time interval which was confirmed by SEC analyses.

We describe a protocol to synthesize alternating telechelic ROMP copolymers of 7-oxa-norbornene derivatives and cycloalkenes under catalytic conditions. These copolymers were synthesized using Grubbs' second-generation catalyst. The sterically less hindered backbone double bonds of the resulting alternating copolymers facilitate the chain transfer (secondary metathesis) reactions. In the presence of symmetrical chain transfer agents (CTA), alternating copolymers could be synthesized catalytically. This procedure allows the synthesis of telechelic polymers based on potentially functional 7-oxanorbornene derivatives under thermodynamic equilibrium conditions. The molar mass of the alternating copolymer was controlled by the monomer to CTA ratio. The end group of the copolymers synthesized in the catalytic manner was addressed by the CTA functionality, yielding telechelic copolymers in excellent yields. 1 H NMR spectroscopy, MALDI-ToF mass spectrometry, and SEC analysis confirmed the chemical identity of the alternating telechelic copolymers with excellent control over the molar mass.

Herein we report the facile synthesis of an amphiphilic rod-coil block copolymer obtained by the coupling of an amine terminated poly(dimethylpropylamine norbornene imide) (PDMNI) and a pentafluorophenol ester terminated poly(dimethoxybenzyl paraaminobenzoate) (PAram). Post-polymerization amide N-deprotection of the block copolymer yielded a strongly aggregating water soluble rod-coil copolymer. Transmission electron microscopy revealed the formation of large ribbon-like aggregates with sizes up to 50 nanometers in thickness and 300 nanometers in length. ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Experimental procedures, 1 H, 13 C-NMR spectra and GPC elugrams.

An efficient method for the regioselective synthesis of uracil-, coumarin-and quinolone-fused benzosultams and benzosultones is reported. The method offers a synthetic route to highly functionalized sultam and sultone derivatives in 75-95% yield under mild conditions. Density functional theory studies have been used to explain the regioselectivity in the synthesis of the coumarin-and quinolone-fused sultams and sultones.

Native chemical ligation (NCL) allows the chemical synthesis of proteins and peptides with excellent efficiency, starting from a mixture of unprotected short peptide fragments. The chemo-and regioselectivity of NCL provide access to functional biomacromolecules such as peptides without protection−deprotection strategies under mild conditions. In contrast, less progress has been made in non-natural polymer conjugation. Metal contamination, synthetic difficulties, laborious purifications, or lack of functional group tolerance limits the complex functional polymer design. Here, we have studied the potential of NCL for non-natural polymer conjugation. Diblock and ABA triblock copolymers were synthesized via NCL with high efficiency within 1 h at room temperature. An A-alt-B block copolymer was also synthesized with a remarkable degree of polymerization from bifunctional thioester and cysteine end functional polymers. The size exclusion chromatography and NMR spectroscopy analyses of the synthesized polymers confirmed the block structure of the polymers and the excellent efficiency of NCL for non-natural polymer conjugation.