Studies of the chemistry of sulfoximines, 2, 1 benzothiazines and cyclopentadienones
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The N-Acylation of a sulfoximine with carboxylic acids was accomplished with boric acid and several boronic acids. Aliphatic acids give fair yields of products while acids related to phenylacetic and phenoxy acetic acids perform much better. Aromatic acids are ineffective in this process. The formation of an interesting benzothiazine from the reaction of S-o-halophenyl-S-methyl sulfoximines in the presence of copper salts is reported. The product's structure was confirmed by spectroscopic and single-crystal X-ray crystal analysis. The benzothiazine shows fluorescent properties. O-Halo sulfoximines show lower reactivity in Buchwald Hartwig coupling reactions than sulfoximines. One pot procedure to obtain o-halo benzothiazines in decent yields is developed. Some derivatives of 2-hydroxy cyclopentenone esters have been synthesized and their reactivity in Diels-Alder reaction has been evaluated. It is found that the derivative containing phosphate ester leaving group gives better yields in Diels-Alder reaction among the derivatives. The yields of the DA adducts were lower due to the rapid decomposition of the reactive intermediate cyclopentadienone. The effect of Lithium ion concentration in the intramolecular stereoselective Michael reaction of a sulfoximine with α, β unsaturated esters is studied. With the use of complexating agents such as HMPA, only one isomer is produced. Using the benzothiazine methodology developed in our group, efforts towards the synthesis cis-calamenene, one of the anti-infective sesquiterpenes is reported.
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