Defense Date

1995

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Suzanne M. Ruder

Abstract

A variety of substituted phosphonium salts, phosphorus ylides and phosphonates were studied to assess their utility in ring expansion reactions. The strategy involved formation of fused ring systems whose ring strain could be exploited to accomplish ring expansion to medium sized rings. β-Alkoxy vinylphosphonium salts were found to be unreactive with species such as the dimethylsulfoxonium methylide anion, Simmons-Smith type reagents. and carbenes in attempts to produce cyclopropyl phosphonium salts.

C-Alkylation of β-keto phosphorus ylides using haloalkanes bearing terminal groups that could be converted and reacted with the B-carbonyl, was also examined as a method for accessing strained rings bearing electron donating alkoxy groups and electron withdrawing phosphorus substituents. The presence of C-alkylated phosphonium salt products was detected by NMR analysis of crude reaction mixtures for diiodomethane and dibromoethane, but synthetically useful yields were not obtained except for the reaction with methyl iodide.

Alkynyl phosphonates, however, were found to be adequate substrates for cycloaddition with enamines to yield ring expanded products. This represents the first ring expansion via cycloaddition of alkynyl phosphonates. The reactivities of enamines derived from pyrrolidine or morpholine were compared in the cycloaddition‘ Efficiency in formation of seven and eight member rings from the enamines of cyclopentanone and cyclohexanone were thus examined. The unsaturated medium sized rings thus obtained were probed for their utility in Michael addition. This method may provide access to the basic framework of a number of natural products found to have biological activity.

Comments

Scanned, with permission from the author, from the original print version, which resides in University Archives.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

2-15-2018

Included in

Chemistry Commons

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