Thesis-1972-Ley.pdf (9.95 MB)

Studies in the chemistry of benzobicyclo systems

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posted on 04.02.2011, 14:13 by Steven V. Ley
Reactions of tetrahalogenobenzynes with certain tertiary arylamines afford products which are derived by both 1,2- and 1,4-cyclo-addition as well as from a betaine. The tetrahalogenobenzynes and benzyne react with eneamines to give benzocyclobutene-derivatives via betaines; the tetrahalogenobenzyne derivatives are readily hydrolysed to 2-tetrahalogenophenyl cycloalkanones. 1-N-alkylamino derivatives of 5,6,7,8-tetrahalogeno-1,4-dihydronaphthalene also undergo cleavage reactions in protic media. Thus, for example, 1-N, N-dimethylamino-tetrafluorobenzobarrelene gives 2,3,4,5- tetrafluoro-k'-N, N-dimethylaminobiphenyl in high yield and 1,2,3,1- tetrafluoro-5,8-dihydro-5,8-N-(-methyl)-iminonaphthalene affords 2'- (2,3,4,5-tetrafluorophenyl)-N-methyl. pyrrole. Apparent similarities between mass spectral and thermal processes have been investigated in connection with retro-Diels-Alder reactions leading to k, 5,6,7-tetrahalogeno-isobenzofurans and 1,5,6,7-tetrafluoro- 2-methylisoindole. These derivatives are more stable than the nonhalogenated compounds. The rearrangement reactions of 1-methoxybenzobarrelene derivatives in strong acids have been studied. Various possible mechanistic pathways have been investigated by deuterium labelling methods. Benzobicyclo[3.2.1] derivatives arise via a 2-carbonium ion while a 3-carbonium ion leads to benzobicyclo[2.2.2)dien-2-one derivatives. The solvolyses of certain toluene-p-sulphonates have been used to check mechanistic predictions. The position of protonation and the extent of the rearrangement can be controlled by the use of alkyl substituents. Thus 2,6-dimethyl-l-methoxytetrafluorobenzobarrelene affords only derivatives of benzobicyclo[3.2.1]- octadiene while 3,5-dimethyl-l-methoxy-tetrafluorobenzobarrelene gives products derived by rearrangement to the benzobicyclo[2.2.2] system.

History

School

  • Science

Department

  • Chemistry

Publisher

© Steven Victor Ley

Publication date

1972

Notes

Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.

EThOS Persistent ID

uk.bl.ethos.463214

Language

en

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