{"id":{"repo_id":"cent-lancashire","oai_identifier":"oai:clok.uclan.ac.uk:20362"},"canonical_url":"https://search.dev.ndltd.org/etd/cent-lancashire/oai:clok.uclan.ac.uk:20362","repository":{"repo_id":"cent-lancashire","name":"University of Central Lancashire","base_url":"https://clok.uclan.ac.uk/cgi/oai2"},"display":{"title":"Studies in Xanthone chemistry","abstract":"A series of 3,4-dihydro-9H-xanthen- 1 ,9(2H)-diones has been prepared by the condensation of 2-fluorobenzoyl chlorides with cyclohexane- I ,3-diones followed by Fries rearrangement and cyclisation of the intermediate 3-oxocyclohexenyl 2-fluorobenzoates. Conversion to spim[ 1 ,2,3,4-tetrahydro-9H-xanthen- 1 ,2'-[ 1 ,3] -dioxolane] -9-one occurred on treatment of the xanthendione with ethane- 1 ,2-diol and trimethylsilyl chloride. 3,4-Dihydro-4-methyl-9H-xanthen- 1 ,9(2H)-dione has been synthesised by quenching the lithium dienolate of the ketal with iodomethane. Conjugate reduction of the xanthendione has been accomplished using sodium borohydride in pyridine to give 1hydroxy-2,3,4,4a-tetrahydro-9H-Xanthen-9-one whose chemistry has been investigated. Treatment of the xanthendione with tris(methylthio)methyllithium gave the 1,4-adduct. Subsequent mercuric ion catalysed solvolysis provided methyl 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-one-4a-carboxylate which is the parent nng of the secalonic acid series of natural products. 4a-Alkyl derivatives have been prepared in excellent yield from the xanthendione and organocyanocuprate reagents. The corresponding Grignard reagents displayed less selectivity in their mode of addition. Reaction of the 1 -hydroxytetrahydroxanthones with hydroxylamine gave 4-substituted 6,7-dihydro-3-(2-hydroxyphenyl)-2, I -benzisoxazoles resulting from ring cleavage of the xanthone nucleus. Dehydrogenation of these systems with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and with palladium on charcoal catalyst has been explored. Treatment of 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-ones with lithium diisopropylamide in tetrahydrofuran afforded dianions which provided an entry to 2-functionalised derivatives by quenching with electrophiles. Acid catalysed treatment of 1hydroxy2,3,4,4a-tetrahydro-9H-xanthen-9-One gave 3,4-dihydro-9H-xanthen-9-one by way of a retro-Michael ring cleavage-bond switch operation. The substituted analogues behaved similarly, although the products were dependent upon the nature of the substituents present. The value of some 3,4-dihydro-9H-xanthen-9-ones as dienes in [4+21-cycloaddition reactions has been established with a variety of dienophiles. The chemistry of some 2-(2-fluorobenzoyl)- I -hydroxy-2,3,4,4a-tetrahydroxanthones has been investigated. Treatment with DBU in toluene led to 4-(2-hydroxybenzoyl)- 9H-xanthen-9-ones, whereas with potassium carbonate in acetone novel 5H,13H-[l]benzopyrano[2,3 -ajxanthen -5, 1 3-diones were obtained. The mechanism of formation for these compounds is discussed.","abstract_html":"A series of 3,4-dihydro-9H-xanthen- 1 ,9(2H)-diones has been prepared by the condensation of 2-fluorobenzoyl chlorides with cyclohexane- I ,3-diones followed by Fries rearrangement and cyclisation of the intermediate 3-oxocyclohexenyl 2-fluorobenzoates. Conversion to spim[ 1 ,2,3,4-tetrahydro-9H-xanthen- 1 ,2'-[ 1 ,3] -dioxolane] -9-one occurred on treatment of the xanthendione with ethane- 1 ,2-diol and trimethylsilyl chloride. 3,4-Dihydro-4-methyl-9H-xanthen- 1 ,9(2H)-dione has been synthesised by quenching the lithium dienolate of the ketal with iodomethane. Conjugate reduction of the xanthendione has been accomplished using sodium borohydride in pyridine to give 1hydroxy-2,3,4,4a-tetrahydro-9H-Xanthen-9-one whose chemistry has been investigated. Treatment of the xanthendione with tris(methylthio)methyllithium gave the 1,4-adduct. Subsequent mercuric ion catalysed solvolysis provided methyl 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-one-4a-carboxylate which is the parent nng of the secalonic acid series of natural products. 4a-Alkyl derivatives have been prepared in excellent yield from the xanthendione and organocyanocuprate reagents. The corresponding Grignard reagents displayed less selectivity in their mode of addition. Reaction of the 1 -hydroxytetrahydroxanthones with hydroxylamine gave 4-substituted 6,7-dihydro-3-(2-hydroxyphenyl)-2, I -benzisoxazoles resulting from ring cleavage of the xanthone nucleus. Dehydrogenation of these systems with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and with palladium on charcoal catalyst has been explored. Treatment of 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-ones with lithium diisopropylamide in tetrahydrofuran afforded dianions which provided an entry to 2-functionalised derivatives by quenching with electrophiles. Acid catalysed treatment of 1hydroxy2,3,4,4a-tetrahydro-9H-xanthen-9-One gave 3,4-dihydro-9H-xanthen-9-one by way of a retro-Michael ring cleavage-bond switch operation. The substituted analogues behaved similarly, although the products were dependent upon the nature of the substituents present. The value of some 3,4-dihydro-9H-xanthen-9-ones as dienes in [4+21-cycloaddition reactions has been established with a variety of dienophiles. The chemistry of some 2-(2-fluorobenzoyl)- I -hydroxy-2,3,4,4a-tetrahydroxanthones has been investigated. Treatment with DBU in toluene led to 4-(2-hydroxybenzoyl)- 9H-xanthen-9-ones, whereas with potassium carbonate in acetone novel 5H,13H-[l]benzopyrano[2,3 -ajxanthen -5, 1 3-diones were obtained. The mechanism of formation for these compounds is discussed.","abstract_has_math":false,"creators":["Urquhart, Michael William John"],"institution":"University of Central Lancashire","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1993,"date_issued":"1993-04","date_published":"1993-04","updated_at":"2026-07-24T01:36:10Z","subjects":["F100 - Chemistry"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Urquhart, Michael William John"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1993-04-01"]},{"key":"dc:date.issued","label":"Date","values":["1993-04"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Chemistry"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Central Lancashire"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://knowledge.lancashire.ac.uk/id/eprint/20362/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["phd"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["F100 - Chemistry"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://knowledge.lancashire.ac.uk/id/eprint/20362/1/20362%20Michael%20William%20John%20Urquhart%20Apr93%20Studies%20in%20Xanthone%20Chemistry%20Doctor%20of%20Philosophy%20unpublished%20Apr93%20University%20of%20Central%20Lancashire%20chemistry%20289.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["A series of 3,4-dihydro-9H-xanthen- 1 ,9(2H)-diones has been prepared by the condensation of 2-fluorobenzoyl chlorides with cyclohexane- I ,3-diones followed by Fries rearrangement and cyclisation of the intermediate 3-oxocyclohexenyl 2-fluorobenzoates. Conversion to spim[ 1 ,2,3,4-tetrahydro-9H-xanthen- 1 ,2'-[ 1 ,3] -dioxolane] -9-one occurred on treatment of the xanthendione with ethane- 1 ,2-diol and trimethylsilyl chloride. 3,4-Dihydro-4-methyl-9H-xanthen- 1 ,9(2H)-dione has been synthesised by quenching the lithium dienolate of the ketal with iodomethane. Conjugate reduction of the xanthendione has been accomplished using sodium borohydride in pyridine to give 1hydroxy-2,3,4,4a-tetrahydro-9H-Xanthen-9-one whose chemistry has been investigated. Treatment of the xanthendione with tris(methylthio)methyllithium gave the 1,4-adduct. Subsequent mercuric ion catalysed solvolysis provided methyl 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-one-4a-carboxylate which is the parent nng of the secalonic acid series of natural products. 4a-Alkyl derivatives have been prepared in excellent yield from the xanthendione and organocyanocuprate reagents. The corresponding Grignard reagents displayed less selectivity in their mode of addition. Reaction of the 1 -hydroxytetrahydroxanthones with hydroxylamine gave 4-substituted 6,7-dihydro-3-(2-hydroxyphenyl)-2, I -benzisoxazoles resulting from ring cleavage of the xanthone nucleus. Dehydrogenation of these systems with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and with palladium on charcoal catalyst has been explored. Treatment of 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-ones with lithium diisopropylamide in tetrahydrofuran afforded dianions which provided an entry to 2-functionalised derivatives by quenching with electrophiles. Acid catalysed treatment of 1hydroxy2,3,4,4a-tetrahydro-9H-xanthen-9-One gave 3,4-dihydro-9H-xanthen-9-one by way of a retro-Michael ring cleavage-bond switch operation. The substituted analogues behaved similarly, although the products were dependent upon the nature of the substituents present. The value of some 3,4-dihydro-9H-xanthen-9-ones as dienes in [4+21-cycloaddition reactions has been established with a variety of dienophiles. The chemistry of some 2-(2-fluorobenzoyl)- I -hydroxy-2,3,4,4a-tetrahydroxanthones has been investigated. Treatment with DBU in toluene led to 4-(2-hydroxybenzoyl)- 9H-xanthen-9-ones, whereas with potassium carbonate in acetone novel 5H,13H-[l]benzopyrano[2,3 -ajxanthen -5, 1 3-diones were obtained. The mechanism of formation for these compounds is discussed."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Studies in Xanthone chemistry"]}]}],"canonical_facts":{"dc:creator":["Urquhart, Michael William John"],"dc:date":["1993-04-01"],"dc:date.issued":["1993-04"],"dc:description.abstract":["A series of 3,4-dihydro-9H-xanthen- 1 ,9(2H)-diones has been prepared by the condensation of 2-fluorobenzoyl chlorides with cyclohexane- I ,3-diones followed by Fries rearrangement and cyclisation of the intermediate 3-oxocyclohexenyl 2-fluorobenzoates. Conversion to spim[ 1 ,2,3,4-tetrahydro-9H-xanthen- 1 ,2'-[ 1 ,3] -dioxolane] -9-one occurred on treatment of the xanthendione with ethane- 1 ,2-diol and trimethylsilyl chloride. 3,4-Dihydro-4-methyl-9H-xanthen- 1 ,9(2H)-dione has been synthesised by quenching the lithium dienolate of the ketal with iodomethane. Conjugate reduction of the xanthendione has been accomplished using sodium borohydride in pyridine to give 1hydroxy-2,3,4,4a-tetrahydro-9H-Xanthen-9-one whose chemistry has been investigated. Treatment of the xanthendione with tris(methylthio)methyllithium gave the 1,4-adduct. Subsequent mercuric ion catalysed solvolysis provided methyl 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-one-4a-carboxylate which is the parent nng of the secalonic acid series of natural products. 4a-Alkyl derivatives have been prepared in excellent yield from the xanthendione and organocyanocuprate reagents. The corresponding Grignard reagents displayed less selectivity in their mode of addition. Reaction of the 1 -hydroxytetrahydroxanthones with hydroxylamine gave 4-substituted 6,7-dihydro-3-(2-hydroxyphenyl)-2, I -benzisoxazoles resulting from ring cleavage of the xanthone nucleus. Dehydrogenation of these systems with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and with palladium on charcoal catalyst has been explored. Treatment of 1 -hydroxy-2,3,4,4a-tetrahydro-9H-xanthen-9-ones with lithium diisopropylamide in tetrahydrofuran afforded dianions which provided an entry to 2-functionalised derivatives by quenching with electrophiles. Acid catalysed treatment of 1hydroxy2,3,4,4a-tetrahydro-9H-xanthen-9-One gave 3,4-dihydro-9H-xanthen-9-one by way of a retro-Michael ring cleavage-bond switch operation. The substituted analogues behaved similarly, although the products were dependent upon the nature of the substituents present. The value of some 3,4-dihydro-9H-xanthen-9-ones as dienes in [4+21-cycloaddition reactions has been established with a variety of dienophiles. The chemistry of some 2-(2-fluorobenzoyl)- I -hydroxy-2,3,4,4a-tetrahydroxanthones has been investigated. Treatment with DBU in toluene led to 4-(2-hydroxybenzoyl)- 9H-xanthen-9-ones, whereas with potassium carbonate in acetone novel 5H,13H-[l]benzopyrano[2,3 -ajxanthen -5, 1 3-diones were obtained. The mechanism of formation for these compounds is discussed."],"dc:format":["application/pdf"],"dc:identifier.uri":["https://knowledge.lancashire.ac.uk/id/eprint/20362/1/20362%20Michael%20William%20John%20Urquhart%20Apr93%20Studies%20in%20Xanthone%20Chemistry%20Doctor%20of%20Philosophy%20unpublished%20Apr93%20University%20of%20Central%20Lancashire%20chemistry%20289.pdf"],"dc:language":["en"],"dc:publisher.department":["Chemistry"],"dc:publisher.institution":["University of Central Lancashire"],"dc:relation.isreferencedby":["https://knowledge.lancashire.ac.uk/id/eprint/20362/"],"dc:subject":["F100 - Chemistry"],"dc:title":["Studies in Xanthone chemistry"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T01:36:10Z"}