Bisurea derivative

Suramin Sodium. Suramin. sodium is a high-molecular-weight bisurea derivative containing six sulfonic acid groups as their sodium salts. It was developed in Germany shortly after World War I as a by-product of research effons directed toward the development of potential antiparasitic agents from dyestuffs. 

The crude product obtained was purified by column chromatography over silica gel with 1 1 ethyl acetate-hexane as the eluant to secure the final compound (229) in 55% yield. Careful isolahon and characterization showed that one of the major by-products of this reaction to be the bisurea derivative (259) in yields of up to 20%. We explored phe-nylchloroformate as a substitute to triphosgene in the preparation of unsymmetrical urea derivatives. Phenylchloroformate (260) in the presence of an appropriate base on reaction with an amine (241) gave the corresponding carbamate, which on further reaction with A-methyl hydroxylamine gave a urea derivative (229). However, the formation of bisurea... 

The achiral bisurea derivatives 152-154 possessing terminal benzyl groups and 155-157 with terminal alkyl chains of variable lengths were studied by van Esch and Feringa (Scheme 22) [106,107]. The compounds exhibited efficient gelation of 1- and 2-octanol, toluene, tetralin, -butyl acetate, cyclohexanone, and hexadecane. Gelators were prepared in high yields by reaction of alkyl or benzyl isocyanates with the respective amines. 

Mono- and bisurea derivatives containing L-Ser and l-G1u alkyl and alkyl methacrylate ester groups were designed as polymerizable organo-gelators [120]. The L-Ser derivative 179, and l-G1u derivatives 180 and 181, (Scheme 26) exhibited efficient gelation of ethylene glycol, hexane, ethyl ac-... 

In addition to rigid bisurea macrocycles, more flexible bisurea-derived macrocycles can also form tubular assemblies in the solid state. For example, Rangana-than and co-workers reported that macrocyclic bisureas prepared from L-cystine was able to form nanotubes of uniform shape and internal diameter [52], The two adjacent rings were bound together by two hydrogen bonds from bisamides and four hydrogen bonds from bisureas. The tubular structure was further stabilized by... 

Fig. 28 Unidirectional intermolecular hydrogen bonding between substituted ureas (top), preparation of gelling froMS-bisurea cydohexane derivatives 149 and 150 and their self-assembly by intermolecular hydrogen bonding left), and the nongelling cis derivative 151...

Scheme 26 Synthesis of polymerizable monourea L-Ser gelator 179 (a) EDCl, DMAP (b) H2, Pd/C (c) methacr)do)d chloride (d) TEA, CH2CI2, and bisurea l-G1u derivatives 180 and 181 (e) TEA, CH3(CH2)5NCO and bisurea l-G1u derivatives 180 and 181 (f) HO(CH2)xOCOC(CH3) = GHz (g) OCN(CH2)i2NCO...

Photocycloaddition of coumarin derivatives functionalized by Si02 nanoparticles or based on self-assembled monolayer afforded [2 + 2] photocycloadducts (273). " Self-assembled phenylethynylene bisurea macrocycles and cucurbit[8]uril (CB[8j) catalyzed the photodimerization of coumarin derivatives " It is noticeable that four dimers of coumarin and 6-alkylcoumarin were easily cleaved to the corresponding monomers. 1,1-Dimethylnaphthalenone photodimerized to give head-to-head cyclobutane, which was photocleavable linkers. ... 

Odagi, M. Furukori, K. Yamamoto, Y Sato, M. lida, K. Yamanaka, M. Nagasawa, K. Origin of Stereocontrol in Guanidine-Bisurea Bifunctional Organocatalyst That Promotes a-Hydroxylation of Tetralone-Derived P-Ketoesters Asymmetric Synthesis of P- and y-Substituted Tetralone Derivatives via Organocatalytic Oxidative Kinetic Resolution. J. Am. Chem. Soc. 2015, 137, 1909-1915. 

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