William Feld (Committee Member), Daniel Ketcha (Committee Member), Kenneth Turnbull (Advisor)
Master of Science (MS)
In the present work, microwave chemistry was utilized to improve and optimize two methods for the acylation of sydnones. Whereas before, 4-acyl-3-arylsydnones could be synthesized by the use of Friedel-Crafts reactions utilizing either Montmorillonite K-10 or bismuth(III) triflate/lithium perchlorate as catalysts in moderate to good yields after long reaction times, with the introduction of microwave chemistry 4-acyl-3-arylsydnones can be synthesized in good to excellent yields in much shorter times. A previous method using Montmorillonite K-10 allowed for a variety of 4-acetyl-3-arylsydnones to be synthesized thermally in moderate to good yields after at least 24 hours. This method was extended in this work to include other acyl species such as 4-propionyl-, 4-butyryl-, and 4-isobutyryl-phenylsydnone. It was attempted also to extend this method to the synthesis of 4-trifluoroacetyl-3-phenylsydnone but without success. However, all of these thermal methods had reaction times of at least 24 hours and some took many days. As such it was of interest to see if microwave irradiation (MWI) could decrease the reaction times and/or improve the yields, which were at best 61%. The yields were not much improved by the method created, optimized and presented in this work, however the reaction times were significantly decreased to as little as one hour.
Another thermal method allowed for the synthesis of these materials in greater yields but using the less "green" catalyst of bismuth triflate and lithium perchlorate. However, as with the previous thermal method, the more complex the anhydride the longer the reaction times, which ranged from at least 2 hours to overnight or longer. A MWI method was developed, and is presented here, which allowed for the synthesis of 4-acetyl-, 4-propionyl-, 4-butyryl- and 4-isobutyryl-3-phenylsydnones in better yields than achieved by Fisher (88-94%) and in much shorter reaction times (15-45 minutes). It was also attempted to utilize this MWI method in the syntheses of 4-benzoyl-3-phenylsydnone and 4-(3-carboxypropanoyl)-3-phenylsydnone, however neither method succeeded and neither was explored further due to lack of time. The overall method developed should be amenable to further development in the manner of different starting materials, such as the o-substituted 3-arylsydnones, and different anhydrides that have not been explored previously.
Department or Program
Department of Chemistry
Year Degree Awarded
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