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Abstract To a solution of the thiol (5 g, 31 mmol) in ethanol, hydrazine hydrate (3.1 g, 62mmol) was added. The mixture was heated under reflux for 30 min. The solid product formed after cooling was collected by filtration, to afford yellow powder precipitate in 85% yield(Scheme 1). Reaction with sugar: A mixture of compound (1) (0.48g, 3mmol), appropriate sugar (3.1 mmol) , (15 ml)absolute ethanol and catalytic amount of glacial acetic acid (3 drops) was heated under reflux for 6h.the formed precipitate was filtered off, dried and recrystallized from ethanol (Schemes2-5). Summary II Summary III Cyclization: A mixture of compound 2-5(0.5g, 1.6m mol) was dissolved in suitable amount of acetic anhydride. The reaction mixture was heated under reflux for 6h. The reaction mixture was poured into ice water and extracted with ethyl acetate. Organic layers were collected, dried with calcium chloride anhydrous and filtered and the solvent was evaporated under reduced pressure( schemes6-9). Summary IV N N NHN HO OH CH2OH OH HO Reflux Scheme 8 4 8 Ac2O N N N N Ac OAc OAc OAc OAc CH2OA c Acetylation: A solution of compound 2-3-4-5 (0.5g, 1.6mmol) in a mixture of acetic anhydride (10ml) and anhydrous pyridine (10ml) was stirred at room temperature for 24h.the reaction mixture was poured into ice water and extracted with ethyl acetate. Organic layers were collected, dried with calcium chloride anhydrous , filtered and the solvent was evaporated under reduced pressure(schemes 10-13). Summary V Scheme 10 4 N N NHN HO OH CH2OH OH HO N N NHN AcO OAc CH2OAc OAc AcO Ac2O/Stirring Pyridine 10 Summary VI Scheme 13 N N NHN HO OH OH CH2OH N N NHN AcO OAc OAc CH2OAc AC2O/Stirring Pyridine 5 13 Prepration of reagent: A mixture of anhydrous sodium acetate (0.98 g, 12 mmol),hippuric acid (3.3 g, 12 mmol), (10 ml) of acetic anhydride and theappropriate aldehyde or ketone was heated for 3h. The solid product formed was collected by filtration( scheme14). Scheme 14 HN Ph COOH O N O O OMe Ph MeO CHO H Ac2O/Sod acetate N O O Cl Ph H Cl CHO Ac2O/Sod acetate 14 15 Summary VII Reaction with reagent: A mixture of compound 1(0.1 g, 0.57 mmol) and 14 or 15 (0.57 mmol) in (20 ml) of dioxane and acetic acid (3drops) was refluxed for 24h. The reaction mixture was poured into ice water. The solid product formed was collected by filtration (scheme15). Reaction of 1 with aldehydes: A mixture of 2 (0.3g, 1.9m mol) and appropriate aldehyde (1.9m mol) in (10 ml) of ethanol in the presence of few drops of glacial acetic acid was refluxed for 6h(scheme16). |