Reactions of 4-chloro-2,6-dimethoxypyrimidine and 2-chlorothiazole with carbanion nucleophiles
| dc.contributor.author | Dillender, Samuel C. | en |
| dc.contributor.committeechair | Wolfe, James F. | en |
| dc.contributor.committeemember | Hudlicky, Milos | en |
| dc.contributor.committeemember | McGrath, James E. | en |
| dc.contributor.committeemember | Ogliaruso, Michael A. | en |
| dc.contributor.committeemember | Mason, John G. | en |
| dc.contributor.department | Chemistry | en |
| dc.date.accessioned | 2017-03-10T15:15:03Z | en |
| dc.date.available | 2017-03-10T15:15:03Z | en |
| dc.date.issued | 1984 | en |
| dc.description.abstract | Reactions of 4-chloro-2,6-dimethoxypyrimidine (1) with enolates of acetone, pinacolone, diisopropyl ketone, and ethyl phenylacetate generated by means of potassium amide in 1 liquid ammonia were found to proceed by the S<sub>RN>1 mechanism upon photostimulation with near-UV light to give good yields of substitution products resulting from displacement of chloride ion. Both photostimulated and dark reactions of 4-chloro-2,6-dimethoxypyrimidine (1) with the carbanions of acetonitrile and propionitrile proceed exclusively by an ionic mechanism in liquid ammonia or THF to give a mixture of monosubstitution products resulting from displacement of chloride or the 6-methoxy substituent. With the acetonitrile carbanion the product resulting from displacement of methoxide was the major substitution product, while reaction of 1 with propionitrile carbanion afforded a preponderance of the product resulting from chloride displacement. Photostimulated reaction of 2-chlorothiazole (2) with the potassium enolate of pinacolone proceeds by a radical-chain mechanism to give the substitution product resulting from chloride displacement. However, when 2 is allowed to react with pinacolone enolate in the dark a completely unexpected product is formed. Under these conditions, the tertiary alcohol, 2-(2-chlorothiazol-4-yl)-3,3-dimethyl-2-hydroxybutane, was formed in which the pinacolone unit had been incorporated in an aldol fashion at the 4-position of 2. Both photostimulated and dark reactions of 2 with the enolate of diisopropyl ketone produced a similar carbinol, 3-(2-chlorothiazol-4-yl)-2,4-dimethyl-3-hydroxypentane, in good yields. Treatment of 2 with potassium amide in liquid ammonia or LDA in THF followed by addition of benzophenone afforded 2-chloro-4-(diphenylhydroxymethyl) thiazole in excellent yield. Trapping experiments with deuterium oxide and iodomethane provide evidence that such aldol-type reactions take place via initial metalation of 2 at position-4, followed by reaction of the resulting carbanion with the appropriate electrophile. This is the first example of direct metalation occurring at the 4-position of a thiazole derivative. | en |
| dc.description.degree | Ph. D. | en |
| dc.format.extent | vii, 137, [2] leaves | en |
| dc.format.mimetype | application/pdf | en |
| dc.identifier.uri | http://hdl.handle.net/10919/76069 | en |
| dc.language.iso | en_US | en |
| dc.publisher | Virginia Polytechnic Institute and State University | en |
| dc.relation.isformatof | OCLC# 10993348 | en |
| dc.rights | In Copyright | en |
| dc.rights.uri | http://rightsstatements.org/vocab/InC/1.0/ | en |
| dc.subject.lcc | LD5655.V856 1984.D566 | en |
| dc.subject.lcsh | Substitution reactions | en |
| dc.title | Reactions of 4-chloro-2,6-dimethoxypyrimidine and 2-chlorothiazole with carbanion nucleophiles | en |
| dc.type | Dissertation | en |
| dc.type.dcmitype | Text | en |
| thesis.degree.discipline | Chemistry | en |
| thesis.degree.grantor | Virginia Polytechnic Institute and State University | en |
| thesis.degree.level | doctoral | en |
| thesis.degree.name | Ph. D. | en |
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