JULIA-KOCIENSKI APPROACH TO 4-SUBSTITUTED 1- ALKENYL-1H-1,2,3-TRIAZOLES

<p>A modular approach to the synthesis of 4-substituted N-vinyltriazoles was<br />developed. The triazole cores were assembled by copper-catalyzed 1,3-dipolar<br />cycloaddition of 1-phenyl-1H-tetrazol-5-yl (PT) azidomethyl sulfide with: pmethoxyphenyl, 2-pyridyl, and triisopropylsilyl alkynes. Subsequent oxidation of the sulfides furnished 4-substituted triazoles with a Julia-Kocienski olefination handle attached at the N1 atom of the triazole. Olefination reactions of triazole-derived Julia-Kocienski reagents with paraformaldehyde gave 1-ethenyl-1H-1,2,3-triazoles. Heck reactions of these products with phenyl or p-methoxyphenyl iodide led to further functionalization of the terminal carbon, with E/Z-olefin ratios ≥ 92%. Heck reaction with p-cyanophenyl iodide gave low conversion, and that with 2-thienyl iodide did not proceed. On the other<br />hand, Julia-Kocienski olefinations proceeded with electron-rich and electron-deficient aryl, as well as alkyl aldehydes. The resulting 1,2-disubstituted alkenes were formed in good yields, but with moderate to poor E/Z-selectivities. A modular approach to the synthesis of 4-substituted N-vinyltriazoles was<br /> developed. The triazole cores were assembled by copper-catalyzed 1,3-dipolar<br /> cycloaddition of 1-phenyl-1H-tetrazol-5-yl (PT) azidomethyl sulfide with: pmethoxyphenyl, 2-pyridyl, and triisopropylsilyl alkynes. Subsequent oxidation of the sulfides furnished 4-substituted triazoles with a Julia-Kocienski olefination handle attached at the N1 atom of the triazole. Olefination reactions of triazole-derived Julia-Kocienski reagents with paraformaldehyde gave 1-ethenyl-1H-1,2,3-triazoles. Heck reactions of these products with phenyl or p-methoxyphenyl iodide led to further functionalization of the terminal carbon, with E/Z-olefin ratios ≥ 92%. Heck reaction with p-cyanophenyl iodide gave low conversion, and that with 2-thienyl iodide did not proceed. On the other hand, Julia-Kocienski olefinations proceeded with electron-rich and electron-deficient aryl, as well as alkyl aldehydes. The resulting 1,2-disubstituted alkenes were formed in good yields, but with moderate to poor E/Z-selectivities.</p>

Name thesis:degree_name

Master of Science (M.S.)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Chemistry

Year dc:date.available

2016

Author dc:creator

• Tsetan, Kunga

Contributors dc:contributor

• Barbara Zajc
• Mahesh Lakshman
• Urs Jans

• triazole
• cycloaddition
• olefination
• Chemistry

Repository record dc:identifier

https://academicworks.cuny.edu/cc_etds_theses/610

OAI identifier oai:identifier

oai:academicworks.cuny.edu:cc_etds_theses-1612