Part I: 3-phenylcyclobut-2-enone and 3-phenylcyclobutanone derivatives. Part II: Calculation of the delocalization energies of some small-ring systems employing the simple molecular orbital treatment

Citation

Manatt, Stanley Lawrence (1959) Part I: 3-phenylcyclobut-2-enone and 3-phenylcyclobutanone derivatives. Part II: Calculation of the delocalization energies of some small-ring systems employing the simple molecular orbital treatment. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/1JFX-G176. https://resolver.caltech.edu/CaltechETD:etd-02172006-102844

Abstract

Part I:

Catalytic hydrogenation of either 1,1-difluoro-2,2dichloro-3-phenylcyclobutene or 1,1-difluoro-2,2-dichloro-3-phenylcyclobutane gives 1,1-difluoro-3-phenylcyclobutane. Bromination of this compound with N-bromosuccinimide followed by dehydrobromination with one mole of ethanolic potassium hydroxide gives good yields of 1,1-difluoro-3-phenylcyclobut-2-ene. Careful hydrolysis of this material with concentrated sulfuric acid gives 3-phenylcyclobut-2-enone. Treatment of 3-phenylcyclobut-2-enone with dilute aqueous sodium hydroxide opens the ring to give benzoylacetone. Ring-opening of 3-phenylcyclobut-2-enone in acetic acid gives [beta]-methyl-cinnamic acid. Reduction of 3-phenylcyclobut-2-enone by sodium borohydride in methanol gives 3-phenylcyclobut-2-enol.

The reaction of phosphorus pentachioride with several 3-phenylcyclobut-2-enones was found to give good yields of gem-dichlorides. Concentrated sulfuric acid hydrolysis of these gem-dichlorides in most cases regenerated the corresponding 3-phenylcyclobut-2-enone.

Catalytic reduction of 2-chloro-3-phenylcyclobut-2-enone gives 3-phenylcyclobutanone. The reduction of this ketone by several reagents is described. Reduction of 2-chloro-3-phenylcyclobut-2-enone by sodium borohydride in methanol gives 2-chloro-3-phenylcyclobut-2-enol. Catalytic hydrogenation of this alcohol gives cis-3-phenylcyclobutanol.

The rates of the acid-catalyzed hydrolysis in "80%" acetone-water, of the 4-nitrobenzoates of cinnamyl alcohol, methylstyrylcarbinol, cyclobutanol, cis- and trans-3-phenyl-cyclobutanol, 2-chloro-3-phenylcyclobut-2-enol, and 3-phenylcyclobut-2-enol, are described. The importance of 1,3-interaction in the 3-phenylcyclobut-2-enyl carbonium ion is discussed. It has been concluded that the acid-catalyzed hydrolysis of 4-nitrobenzoate esters is not a satisfactory means of studying relative carbonium ion stabilities.

Part II:

The simple molecular orbital method (LCAO) has been used to calculate the electron delocalization energies of number of small-ring compounds in order to see which might be predicted to be reasonably stable on theoretical grounds. Included are a number of phenyl-substituted cyclobutadienes, benzocyclobutadienes, cyclobutadienoquinones, cyclobutenes, cyclobutenones, methylenecyclopropenes, cyclopropenones, phenyl-substituted cyclopropenyl cations, and several miscellaneous cyclobutenyl cations. The qualitative significance of the results is discussed.

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