1,1 -thiocarbonyldiimidazol

Table 28 Reaction of carbohydrazonamides with 1,1 -thiocarbonyldiimidazole (Scheme 12)... 

Oxo-l,2,4-thiadiazoles were prepared from the corresponding amidoximes and 1,1 -thiocarbonyldiimidazole/BF3 OEt2 or ClSCOCl/EtsN. Thus, amidoximes 278 and ClSCOCl in the presence of EtsN afforded 1,2,4-thiadiazoles 279 in yields up to 20% (equation 120). 

Reaction of various aromatic or heteroaromatic diamines with iV-acyl isothiocyanates gave the corresponding benzo- or heterocycle-fused l,3,5-triazepine-2-thiones, for example, 16 (Figure 3) from 5,6-diamino-1,3-dimethyl-uracil and D-gluconyl isothiocyanate <1981CPB1832>. Cycloaddition of iVjiV -disubstituted ethylenediamines with bis(isocyanato)dimethylsilane or bis(isothiocyanato)dimethylsilane followed by treatment with 1,1 -carbonyldi-imidazole or 1,1 -thiocarbonyldiimidazole afforded a series of 1,5-disubstituted l,3,5-triazepine-2,4-diones, -2,4-dithiones, and 4-oxo-l,3,5-triazepine-2-thiones <1980AGE327>. 

To a stirred solution of methyl 2,3-di-0-benzyl-6-0-t-butyldiphenylsilyl-a-D-glucopyranoside (0.617 g, 1.01 mmol) in toluene (5 ml) was added 1,1 -thiocarbonyldiimidazole (0.359 g, 2.01 mmol) at room temperature. The solution was heated at reflux. The reaction mixture was poured into 0.5 N HCI (50 ml) and extracted with CH2CI2 (3x50 ml). The organic layers were combined, washed with sat. sodium bicarbonate solution followed by brine, dried over sodium sulfate and filtered. The solvent was removed in vacuum to give a crude yellow oil, which was purified by column chromatography over silica gel (hexane-EtOAc, 7 3) to afford 0.676 g (93%) of methyl 2,3-di-O-benzyl-6-0-t-butyldiphenylsilyl-4-0-imidazolyl-thiocarbonyl-a-D-glucopyranoside as a colorless viscous oil. 

Thiocarbonyldiimidazole (0.8 mmol) dissolved in 5 ml nitromethane was cooled to 4°C, then treated dropwise with methyl triflate (1.6 mmol). The reaction was... 

Another modification made off the C-2 position of 1 is the trichloroacetimidate derivate (104), which was prepared by treating 57 with trichloroacetonitrile and DBU in C1CH2CH2C1 at 0 °C to yield product 104 in a 37% yield (Scheme 16) [39], Efforts were also made to remove the C-2 hydroxyl of 57 entirely. Hydroxyl 57 was treated with 1,1-thiocarbonyldiimidazole and catalytic DMAP in CH2C12 to afford imidazole 105 in 64% yield [50], Imidazole 105 was then refluxed with 2,2 -azobis (2-methylpropionitriIe) (AIBN) and tributyltin hydride in toluene to bestow C-2 dehydroxylated 57 in a C-8 epimeric mixture of C-8 a-H and p-H in 13 and 27% yield (106 and 107), respectively [50], Additionally, dilactone 108 was obtained by treating 57 with a mixture of chromium trioxide and pyridine in CH2C12 in a 37% yield [50],... 

Sun et al. reported a diversity-oriented tactic to access the benzo[d]oxazol-5-yl-lH-benzo[d]imidazole 64 on IL support (Scheme 24). The authors coupled 4-hydroxy-3-nitrobenzoic acid onto IL-immobilized o-phenylenediamine 58 that underwent ring closure to furnish benzimidazole derivatives 60. Further hydrogenation of the nitro group to an amine followed by the reaction with 1,1-thiocarbonyldiimidazols resulted into IL tagged-benzoxazol 63. In order to generate skeletal diversity, S-alkylation with alkyl and aryl bromides was carried out. Cleavage of 64 from IL support was done by treatment with sodium methoxide in methanol imder microwave irradiation [127]. 

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