RESUMEN
Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted 2-aminobenzophenones and thiourea in the presence of dimethyl sulfoxide (DMSO). This is a unique complementary reaction system in which thiourea undergoes thermal decomposition to form carbodiimide and hydrogen sulfide, where the former reacts with 2-aminobenzophenone to form 4-phenylquinazolin-2(1H)-imine intermediate, whilst hydrogen sulfide reacts with DMSO to give methanethiol or other sulfur-containing molecule which then functions as a complementary reducing agent to reduce 4-phenylquinazolin-2(1H)-imine intermediate into 4-phenyl-1,2-dihydroquinazolin-2-amine. Subsequently, the elimination of ammonia from 4-phenyl-1,2-dihydroquinazolin-2-amine affords substituted quinazoline derivative. This reaction usually gives quinazoline derivative as a single product arising from 2-aminobenzophenone as monitored by GC/MS analysis, along with small amount of sulfur-containing molecules such as dimethyl disulfide, dimethyl trisulfide, etc. The reaction usually completes in 4-6 hr at 160 ºC in small scale but may last over 24 hr when carried out in large scale. The reaction product can be easily purified by means of washing off DMSO with water followed by column chromatography or thin layer chromatography.
Asunto(s)
Benzofenonas/síntesis química , Quinazolinas/síntesis química , Ácido Úrico/análogos & derivados , Técnicas de Química Sintética/métodos , Cromatografía/métodos , Dimetilsulfóxido/síntesis química , Dimetilsulfóxido/química , Disulfuros/síntesis química , Microondas , Compuestos de Sulfhidrilo/síntesis química , Sulfuros/síntesis química , Ácido Úrico/síntesis químicaRESUMEN
CONTEXT: A substantial proportion of the patient population with migraine headache should be considered for preventive treatment based on the frequency and disability associated with this disorder. Use of the anticonvulsant topiramate was previously examined in two large, double-blind, randomized, placebo-controlled clinical trials of a subset of patients who have 3 to 12 migraine episodes per month. OBJECTIVE: To better characterize the efficacy of topiramate for prevention of migraine, with or without aura, by pooling and analyzing data from the two large clinical trials. METHODS: The pooled intent-to-treat population included 937 patients receiving topiramate at one of three dosages (50 mg/d, 100 mg/d, 200 mg/d) or placebo. Outcome measures included change in mean monthly migraine frequency and categorical responder rate throughout the 26-week doubleblind phase. RESULTS: At daily doses of 100 and 200 mg, topiramate was associated with significant reductions in mean monthly migraine frequency throughout the double-blind phase compared with placebo (P<.001). Significantly more patients treated with these topiramate doses exhibited high-percentage reductions in monthly migraine frequency (>/=50% [P<.001], >/=75% [P<.001], 100% [P=.049]) versus placebo. The most common adverse events included anorexia, cognitive deficits, diarrhea, fatigue, nausea, and paresthesia. Topiramate (100 mg/d, 200 mg/d) was associated with significant and sustained reductions in mean monthly migraine frequency beginning as early as 1 week into therapy. CONCLUSION: Pooled efficacy data from two large, similarly designed, placebo-controlled migraine-prevention trials demonstrated that a statistically significant proportion of patients using topiramate met or exceeded two main outcome guidelines recommended by the International Headache Society (>/=50% and >/=75% reduction in frequency of monthly attacks). Based on efficacy and tolerability, topiramate at a dosage of 100 mg per day (50 mg twice daily) should be the target dosage for most patients with migraine.