Cycloaddition. -Significant amounts (20-45% NMR) of undesired regioisomers are also generated in some cases. -(MORI, A.; ARAKI, T.; MIYAUCHI, Y.; NOGUCHI, K.; TANAKA*, K.; Eur.

Complementary theoretical and experimental studies of the consecutive steps of superacid catalyzed polyhydroxyalkylation reactions have been carried out. Calculations for the superacid catalyzed polyhydroxyalkylation of trifluoroacetone and trifluoroacetophenone with aromatic hydrocarbons explained a number of experimental facts within a single theoretical framework of monoprotonation. The principal factors affecting kinetics of superacid mediated hydroxyalkylation were shown to be as follows: (i) the acidity of the superacid affecting protonation energy of carbonyl components; (ii) the electrophilicity of carbonyl components; and (iii) the nucleophilicity of aromatic components. The modification of those factors allows for tuning of the reactivity of carbonyl and aromatic components; thereby, reaction kinetics are controlled. The conclusions were confirmed by the experiments. Theoretically predicted stoichiometrically imbalanced polymerizations of trifluoroacetone, trifluoroacetophenone, octafluoroacetophenone, and isatin with nonactivated, aromatic hydrocarbons gave high-molecular-weight polymers with a very small excess of the carbonyl compound. The main reasons contributing to the polymerization accelerations were found to be an increase of the first, rate-determining step reaction, and a high efficiency of the superacid catalyzed polyhydroxyalkylations. The present work has thus opened a new route to preparations of polymers of linear, hyperbranched, or hybrid (e.g., linear−hyperbranched) architecture by operating on structural parameters and reaction conditions.

A versatile photoactivated catalytic system based on a cyclometalated ruthenium(II) complex, composed of strongly coordinating bidentate and relatively labile ligands, in conjunction with a traditional alkyl bromide initiator, has been developed for living/controlled radical polymerization. Polymerizations of three typical hydrophobic monomersmethyl methacrylate (MMA), styrene (St), and n-butyl acrylate (BA)proceeded to high conversions under visible light irradiation. The polymerization process was photoresponsive, i.e., took place only under irradiation and immediately stopped when the light was turned off. Block copolymers of MMA with St and BA with St, as well as statistical copolymer of BA and St, could also be conveniently prepared. 1 H NMR and electrochemical studies suggest a mechanism of the catalytic activation, which involves a photoinduced formation of the solvento 18-electron species cis-[Ru(o-C 6 H 4 -2-py)(phen)(MeCN)(acetone)] + through the intermediacy of the 16-electron five-coordinated complex cis-[Ru(o-C 6 H 4 -2-py)(phen)(MeCN)] + which is believed to be a crucial intermediate of the overall ATRP process.

A novel series of linear, high-molecular-weight polymers was synthesized by one-pot, metalfree superacid-catalyzed reaction of isatins (1a-d) with linear, nonactivated, multiring aromatic hydrocarbons: biphenyl (A), p-terphenyl (B), p-quaterphenyl (C), 2-(4-biphenylyl)-6-phenylbenzoxazole (D), 9Hfluorene (E), 9,9-dimethyl-9H-fluorene (F), 2,2 0 -[2,5-bis(trifluoromethyl)-1,4-phenylene]bis(9,9-dimethyl-9H-fluorene) (G), oligo-9,9-bis(2,6-ethylhexyl)-9H-fluorene (H), biphenol (I), and bi-2-napththol (J). The reactions were performed at room temperature in the Brønsted superacid trifluoromethanesulfonic acid (CF 3 SO 3 H, TFSA) and in a mixture of TFSA with methylene chloride or TFA tolerant of hydroxyl, carboxy, and cyano groups. The polymers obtained were soluble in most common organic solvents, and flexible transparent films could be cast from the solutions. 1 H and 13 C NMR analyses of the polymers synthesized revealed their linear structure with para-substitution in the phenylene fragments of the main chain. The molecular weights M w and M n of the polymers ranged from 54200 to 742000 and from 40140 to 438500 g/mol, respectively. Most of the polymers also possess narrow polydispersity (1.15-1.50). The oxindole groups of the polymers react smoothly with alkyl bromides under basic conditions in N-methylpyrrolidinone (NMP). The amount of "click"able allyl-and propargyl-functionalities is readily controlled by adjusting the reaction ratio of polymer to alkyl bromides. The demonstrated efficiency and orthogonality of isatin-based polymer chemistry shows it to be an essential addition to the family of polymer "click" reactions.

4-Piperidone and 4-alkyl piperidones react selectively with aromatic hydrocarbons in a mixture of trifluoromethanesulfonic acid (TFSA) and CH(2)Cl(2) to give linear polymers, while N-(2-phenethyl)piperidone undergoes self-polymerization to yield virtually 100%-hyperbranched polymer.