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7-O-取代-8-甲基香豆素和4-H-色烯-4-酮化合物是合成Seco-DCK和Seco-DCP类似物的重要中间体.报道了在NBS/CCl4条件下,这两类化合物8-位甲基溴代反应的情况.通过实验发现,这两类化合物8-位甲基溴代反应较一般芳环苄位的溴代更为复杂,存在多个反应位点.影响8-位甲基溴代选择性和收率的主要因素有三:邻位基团空间位阻大小、自由基引发催化剂的使用与否以及邻位基团的电性因素.通过控制反应条件,可以中等收率得到8-位甲基溴代化合物.
7-O-Substituted-8-methylcoumarin and 4-H-Chromen-4-one compounds are important intermediates for the synthesis of Seco-DCK and Seco-DCP analogues.It is reported that under the conditions of NBS / It is found experimentally that the 8-position methyl bromides of these two compounds are more complicated than those of general arylbenzyl bromides and that there are multiple reaction sites The main factors affecting the selectivity and yield of methyl bromide at 8-position are as follows: the size of the steric hindrance of the ortho-group, the use of free radical-initiated catalysts and the electrical properties of ortho-groups. By controlling the reaction conditions , The 8-position methylbromide can be obtained in moderate yield.