Sugar isothiocyanates reactions

A straightforward preparation of pyrimidinones and pyrimidinethiones 45 involved reaction of isocyanates or isothiocyanates with the readily available starting material 44, which had previously been described by the same authors. A particularly interesting application was the use of sugar isothiocyanates to give nucleosides. Nucleophilic displacements of the sulfur groups in the products were also reported <06EJO634>. 

The preparation and reactions of V-thiocarbonyl carbohydrate derivatives, such as sugar isothiocyanates, thioamides, thioureas, thiocarbamates and their conjugates have been the subject of valuable comprehensive as well as specialized accounts, which should be consulted for details.198... 

Derivatization with phenyl isothiocyanate (97, R = Ph) followed by HPLC was compared with IEC followed by the ninhydrin reaction for over ninety compounds. The former method was favored for speed, sensitivity and equipment versatility257. Phenylth-iocarbamyl derivatives of amino sugars and amino sugar alcohols (reaction 10) were... 

The classical, Fischer7 synthesis of sugar isothiocyanates involves treatment of an acylated glycosyl halide with an inorganic thiocyanate in a polar solvent. Depending on the reactivity of the halide and the reaction conditions, either a thiocyanate or an isothiocyanate is formed directly. 

Ogura and Takahashi18,19 detailed the reaction of the sugar isothiocyanates 2, 30, 31, and 32 with ammonia and amines, as well as with various classes of hydrazines. The reaction of sugar isothiocyanates with various classes of amines,44"62 hydrazines,63 72 and hydrazides has been reported by... 

In a series of publications and patents,63 64 66"79 Wieniawski and coworkers reported the results of investigations of the reaction of sugar isothiocyanates with amines and various substituted hydrazides of heterocyclic acids. The reaction of isothiocyanate 2 with 2,6-diaminopyridine 81 was described,63 and the formation of dithioureide 82 as the sole product was observed. The... 

The chemistry of sugar isothiocyanates and their reactions has been the subject of a specialized article in this series by Witczak4 in 1986 with 143 references dating up to 1984. The reader is also referred to the earlier work of Goodman5 on ureido sugars for a thorough historical perspective. It should... 

J. M. Garcia Fernandez, C. O. Mellet, V. M. Diaz Perez, J. Fuentes, J. Kovacs, and I. Pinter, Aza-Wittig reaction of sugar isothiocyanates and sugar iminophosphoranes An easy entry to unsymmetrical sugar carbodiimides, Tetrahedron Lett., 38 (1997) 4161-4164. 

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. 

Another main subject of research of Garcia Gonzalez, with the collaboration of J. Femandez-Bolanos, was the reaction of amino sugars with isothiocyanic acid derivatives. 2-Amino-2-deoxy-D-glucose hydrochloride and potassium thiocyanate were shown to give rise to 4-(D-arabino-tetritol-l-... 

Thioureas are most commonly prepared from reaction of isothiocyanates with amines. Also there are some reports on reactions of anime or carbodiimides with several thionating reagents. AA -Disubstituted thioureas bearing double NH groups have been developed as sensors, and as catalysts because of their hydrogen bonding ability. A,A -Disubstituted thiourea-linked sugar chains have been prepared by the reaction of isothiocyanate with amine. 

In carbohydrate chemistry, the most described method for the preparation of saccharidic thionocarbamates involves preliminary introduction of the amine function on a partially or non-protected saccharidic template. The condensation of amino sugars with carbon disulfide or thiophosgene leads to cyclization in 1,3-oxazolidine- or l,3-oxazine-2-thiones. This reaction involves the formation of an intermediate isothiocyanate, which reacts further with a 3- or y-located hydroxyl group. The viability and facility of this process depends on the saccharidic ring size and the inherent strain. Some major rules can be put into light from the cases studied 30... 

OZTs from aldoses and ketoses. The second and the oldest-as well as the less studied—method is based on the condensation of O-unprotected sugars with thiocyanic acid, generated in situ from potassium thiocyanate and a protic acid. The reaction involves the free anomeric position and a y- or (5-hydroxyl group able to promote intramolecular cyclization of a transient open-chain isothiocyanate, to form the thermodynamically most stable OZT. The first results obtained by Zemplen in d-gluco and D-Fru series reported the formation of OZTs fused to pyran backbones (Scheme 20).42... 

---