19481-79-9

Dialkyl azo compounds were found to be effective alkyl radical sources for direct alkyl sulfuration with imidazopyridines using elemental sulfur under metal-free conditions. Iodine, an inexpensive and mild reagent, could promote alkyl sulfuration. A variety of quaternary cyanoalkyl radicals were successfully coupled with elemental sulfur. A subsequent C-H sulfuration of imidazopyridines afforded a diverse array of imidazopyridine derivatives bearing cyanoalkylthio groups. The cyano group could be modified and further underwent condensation with 2-aminothiazole to afford an interesting heterocyclic amide. Control experiments showed that iodine could greatly suppress the self-coupling of cyanoalkyl radicals, thus making the sulfuration proceed smoothly.

A direct metal-free approach for the synthesis of alpha-cyanoalkylboronic esters from bis-diboron ester and azobis-nitrile compound is reported under ambient temperature and pressure via a free radical procedure.

The objectives of this work were to elucidate the mechanistic pathway of the title reaction, which constitutes the first example of a radical iodine atom transfer addition reaction of non-fluorine-containing phosphonates, and to determine whether 2-iodo-2-methylpropionitrile, 8, can serve as a competing iodine donor with the starting diethyl 1-iodoalkyl phosphonates, 1a,b. The title reaction was found to proceed with AIBN as the sole radical initiator, not requiring poisonous tin reagents as co-initiators, and gave diethyl 3-iodoalkylphosphonates 3a-e (the final products of the propagation step, isolated in 59-95% yield), tetramethylsuccinodinitrile, 9, diethyl methylphosphonate, 4 and tetraethyl ethylenebisphosphonate 5 (all termination products, 0-10% yields). The radical character of this reaction was demonstrated using TEMPO as a radical trap. 8 (the intermediate of the initiation step), synthesized independently from AIBN and iodine, caused complete inhibition of the reaction when added to the reaction mixture, indicating that it does not behave as an iodine donor in the transfer stage, but rather as an inhibitor.

The present invention's purpose is to provide: a molecular-weight controlling agent for radical polymerization which enables controlled radical polymerization of a water-soluble monomer in an aqueous medium; a method for producing a polymer of a water-soluble vinyl monomer using the same; and a water-soluble vinyl monomer polymer. The present invention provides a molecular-weight controlling agent for radical polymerization characterized in that the agent comprises, as its active ingredient, an iodine compound represented by formula (1) and in that the solubility of the active ingredient in water is 0.5 weight % or more at 20° C. In the formula, R1 is —COOX, —CONR4R5, an aromatic group or a cyano group, X is a hydrogen atom, an aliphatic group, an alkali metal, an alkaline earth metal, an organic ammonium or an ammonium, and R2, R3, R4 and R5 are each independently a hydrogen atom, an aromatic group or an aliphatic group.

The decomposition of azoisobutyronitrile (AIBN) and t-butyl phenylperacetate in the presence of toluene-p-sulphonyl bromide and iodide were studied; results are explained on the basis of free radical reactions.The relative reactivities of several alkane- and arene-sulphonyl chlorides towards phenyl, benzyl, and trichloromethyl radicals were measured in competition experiments.Results are rationalized on the grounds of a balance between polar effects in the initial and in the transition state.