Theses and Dissertations

Guozhong Ye

Issuing Body

Mississippi State University

Advisor

Pittman Jr., U. Charles

Committee Member

Sygula, Andrzej

Committee Member

Mead, T. Keith

Committee Member

Foster, C. Stephen

Committee Member

Gwaltney, Steven

Date of Degree

12-13-2008

Document Type

Dissertation - Open Access

Major

Chemistry

Degree Name

Doctor of Philosophy

College

College of Arts and Sciences

Department

Department of Chemistry

Abstract

Cyclic ketene-N,N-acetal chemistry was explored. 2-Methylimidazoline and 2-methyl-1,4,5,6-tetrahydropyrimidine derivatives were prepared from the condensation reactions of diamines with nitriles under Lewis acid catalysis and used as the precursors of cyclic ketene-N,N-acetals including the N-methyl and N-acyl cyclic ketene-N,N-acetals. The reactions of 2-methylimidazoline with excess benzoyl chlorides in THF or MeCN in the presence of triethylamine generate N,N'-diacyl-beta-keto-cyclic ketene-N,N-acetals. The corresponding reactions of 1,2-dimethylimidazoline under the same conditions form the ring-opened (Z)-3-((2-benzamidoethyl)(methyl)amino)-3-oxo-1-phenylprop-1-enyl benzoates. The latter reactions feature the formation of carbon-carbon bonds, carbon-nitrogen bonds, and carbon-oxygen bonds in one operation. The reactions of 2-methyl-1,4,5,6-tetrahydropyrimidine with excess acid chlorides in Et3N/THF generate N,N-diacyl-cyclic ketene-N,N-acetals, with no further acylation on the exocyclic beta-carbons. In contrast, the reactions of 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine under the same conditions form N-acyl-N'-methyl-beta,beta-diketo-cyclic ketene-N,N-acetals, with the dual acylations on the exocyclic beta-carbons. Significant double bond torsion and elongation were observed by the X-ray analysis of an example compound from the latter reactions. The reactions of 2-methylimidazoline and 2-methyl-1,4,5,6-tetrahydropyrimidine with 1,3-diacid chlorides, in the presence of Et3N in refluxing MeCN give highly functionalized potentially bioactive 1,8-naphthyridinetetraones. 2-Methylimidazoline and 2-methyl-1,4,5,6-tetra-hydropyrimidine can be viewed as tridentate nucleophiles which give four consecutive tandem nucleophilic attacks on electrophiles. The reactions of 1,2-dimethylimidazoline and 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine with isocyanates in refluxing MeCN gave bicyclic pyrimidinediones. The reactions of N,N'-dimethyl cyclic ketene-N,N-acetals with various isocyanates generated push-pull alkenes which have never been reported. Significant elongations and torsions of the polarized carbon-carbon double bonds in the novel push-pull alkenes were observed using the X-ray crystallography. The stronger pushing effect of the six-membered cyclic ketene acetal portion in a push-pull alkene, versus the five-membered analog, was detected by reactivity differences for the first time.

URI

https://hdl.handle.net/11668/15585

Comments

imidazoline||tetrahydropyrimidine||ketene acetals||pyrimidinediones||naphthyridinetetraones||push-pull alkenes

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