Title page for ETD etd-042006-160619

Document Type thesis

Author Name ERVITHAYASUPORN, VUTHICHAI

Email Address maldinig at wpi.edu, maldiniandg@hotmail.com

URN etd-042006-160619

Title Synthesis and Photochemistry of Pyrano[2,3-c]pyrazoles

Degree MS

Department Chemistry & Biochemistry

Advisors
Professor James W. Pavlik, Advisor

Keywords
Synthesis
Photochemistry

Date of Presentation/Defense 2006-04-20

Availability unrestricted

Abstract
Two different synthetic approaches to the synthesis of pyrano[2,3-c]pyrazoles have been investigated. In one approach, dehydroacetic acid derivatives were treated with phenylhydrazine and methylhydrazine led to the formation of the phenylhydrazones and methylhydrazones, which undergo rearrangement in refluxing acetic acid to diketo-phenylpyrazoles and diketo-methylpyrazoles. Upon treatment with a mixture of acetic and sulfuric acid these compounds isomerize to the phenylpyrano[2,3-c]pyrazol-4-one and methylpyrano[2,3-c]pyrazol-4-one derivatives.
In a second approach, phenylhydrazine and methylhydrazine reacted with dimethyl(methoxymethylene)malonate (34) to give phenylpyrazole and methylpyrazole ester derivatives which were converted to phenylpyrazolone and methylpyrazolone by hydrolysis and decarboxylation. C-acylation of these compounds with trans-cinnamoyl chloride gave į,ā-unsaturated-4-acetyl-5-hydroxypyrazoles. Bromination of these į,ā-unsaturated-4-acetyl-5-hydroxypyrazoles with spontaneous cyclization, followed by dehydrobromination led to pyrano[2,3-c]pyrazol-4-one derivatives, respectively.
Phototochemical excitation of 1-phenyl and 1-methylpyrano[2,3-c]pyrazol-4-ones in acetonitrile led to the formation of cis-head-to-tail [2+2] cycloaddition products. Irradiation in ethanol solvent led to photodimerization and to photofragmentation to yield pyrazole ethylesters.

Files
Ervithayasuporn.pdf

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Document Type	thesis
Author Name	ERVITHAYASUPORN, VUTHICHAI
Email Address	maldinig at wpi.edu, maldiniandg@hotmail.com
URN	etd-042006-160619
Title	Synthesis and Photochemistry of Pyrano[2,3-c]pyrazoles
Degree	MS
Department	Chemistry & Biochemistry
Advisors	Professor James W. Pavlik, Advisor
Keywords	Synthesis Photochemistry
Date of Presentation/Defense	2006-04-20
Availability	unrestricted
Abstract Two different synthetic approaches to the synthesis of pyrano[2,3-c]pyrazoles have been investigated. In one approach, dehydroacetic acid derivatives were treated with phenylhydrazine and methylhydrazine led to the formation of the phenylhydrazones and methylhydrazones, which undergo rearrangement in refluxing acetic acid to diketo-phenylpyrazoles and diketo-methylpyrazoles. Upon treatment with a mixture of acetic and sulfuric acid these compounds isomerize to the phenylpyrano[2,3-c]pyrazol-4-one and methylpyrano[2,3-c]pyrazol-4-one derivatives. In a second approach, phenylhydrazine and methylhydrazine reacted with dimethyl(methoxymethylene)malonate (34) to give phenylpyrazole and methylpyrazole ester derivatives which were converted to phenylpyrazolone and methylpyrazolone by hydrolysis and decarboxylation. C-acylation of these compounds with trans-cinnamoyl chloride gave į,ā-unsaturated-4-acetyl-5-hydroxypyrazoles. Bromination of these į,ā-unsaturated-4-acetyl-5-hydroxypyrazoles with spontaneous cyclization, followed by dehydrobromination led to pyrano[2,3-c]pyrazol-4-one derivatives, respectively. Phototochemical excitation of 1-phenyl and 1-methylpyrano[2,3-c]pyrazol-4-ones in acetonitrile led to the formation of cis-head-to-tail [2+2] cycloaddition products. Irradiation in ethanol solvent led to photodimerization and to photofragmentation to yield pyrazole ethylesters.
Files	Ervithayasuporn.pdf