Isothiocyanates reaction with aminosugar

The reaction of aminosugar 704 with isocyanates and isothiocyanates has been studied extensively (85AQ(C)147 91M12, 91M13). The reaction gave 703 via the formation of a ureido derivative, which is too reactive to be isolated. The formation of 705 from 704 during the acetylation and deacetylation was studied. 

The reaction of sugar isothiocyanates with aminosugars described above has also been studied with 1-amino (alkyl and arylamino)-l-deoxy-D-fructose 143 (Scheme 32). Thus, treatment of different 0-acylated sugar isoth-iocyanates with D-fructosamines 143 gave M-glycosyl-5-hydroxy-5-tetritolyl-imidazolidine-2-thiones 144 as pairs of diastereomers in almost quantitative yield [ 152]. The reaction times were shorter (15-20 min) for fructosamine or its M-methyl derivatives than in the cases of N-aryl derivatives (8-24 h). Acid-catalyzed dehydration of 144 with ethanolic TFA at rt led to 147 in 65-77% yield. These compounds can be considered simultaneously as M-nucleosides and acyclic C-nucleosides of imidazoline-2-thiones. 

Reaction of isothiocyanates with aminosugars 4-Hydroxyimidazolidine-2-thiones... 

Azine approach. 6-Aminouracils are attacked by electrophiles at C-5. With an isothiocyanate as electrophile a thiocarbamoyl derivative (156) is formed which undergoes oxidative cyclization. Sometimes a minor product, the thiazole (158), may be formed via the thiourea intermediate (157). The course of the reaction may perhaps be rationalized on the HSAB principle the hard iso thiocyanate electrophile has to choose between the hard nucleophilic centre at C-5 or the soft nucleophilic centre at 6-NH2. Isothiocyanates of aminosugars have also been used in these reactions (79CPB1147). 

Thiourea derivatives of daunorubicin have been made by reaction of the aminosugar with ethyl or phenyl- isothiocyanate on -methyl-ation, these derivatives reacted further with amines, the thio-... 

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