Trifluoromethylation of Dihaloarenes: toward Bis(trifluoromethyl) quinazolinespirohexadienone
Dr. Jason G. Gillmore
Our computational studies predict that replacing the methyl groups in our group’s first dimethylquinazolinespirohexadienone (dimethylQSHD) photochrome will make for a much more potent photochromic photooxidant. Previous group members have determined that it is not possible to carry out the synthesis with trifluoromethyl groups present from the start, as they completely inhibit a key nitration step, and devised a synthesis of dihaloQSHDs that could be amenable to installing the trifluoromethyl group at a variety of points later in the synthetic route. Model studies have allowed us to optimize trifluoromethylation reaction conditions. The effects of competing reactions and inhibitors were studied through competition experiments. Together these allowed us to identify the most promising targets for trifluoromethylation in the synthesis of the desired bis(trifluoromethyl)QSHD. However, the desired transformation of the actual compounds has not yet been successfully achieved. Issues of solubility, reaction dilution, loss of compound upon workup, and the development of an internal standard for GC/MS and NMR monitoring of the reaction are all reported.
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