{"id":{"repo_id":"cent-lancashire","oai_identifier":"oai:clok.uclan.ac.uk:19780"},"canonical_url":"https://search.dev.ndltd.org/etd/cent-lancashire/oai:clok.uclan.ac.uk:19780","repository":{"repo_id":"cent-lancashire","name":"University of Central Lancashire","base_url":"https://clok.uclan.ac.uk/cgi/oai2"},"display":{"title":"Reactions and rearrangements of chroman-4-ones and related compounds","abstract":"The synthesis of a range of novel 2,2-disubstituted chroman-4-ones has been accomplished by the pyrrolidine catalysed condensation of a 2-hydroxyacetophenone with aldehydes and ketones. The reaction permits access to both symmetrically and unsymmetrically substituted compounds. The reaction has been extended to the preparation of a novel furochromanone, an analogue of the natural product khellin. The Schmidt reaction of 2,2-disubstituted chroman-4-ones in an acetic-sulphuric acid mixture affords 2,3,4.5-tetrahydro-1.4- benzoxazepine-5(411)--ones, resulting from alkyl migration of the iminodiszonium intermediate. Chroman-4-ones possessing a carbocation stabilising function show anomalous behaviour, the initially formed 1,4-benzoxazepinone being particularly susceptible to protolysis. 2-Methyl-2-phenylchromanone affords a 2-oxazoline as the major product, whilst 2-cyclopropyl-2- methylchromanone gives a mixture of five components which have been separated and characterised. The major products result from hydration and acetolysis of the cyclopropyl carbenium ion. Products resulting from aryl migration and anti-Markovnikov addition of acetic acid to the cyclopropane ring are also formed. Carbanions derived from chromanones have been generated and used to prepare a range of 3-hydroxymethylenechroman-4-ones. Conjugate reduction of the corresponding chromone by sodium borohydride in pyridine provides a simple entry to 3-acetyl and 3-aroyl-2-methylchromanones. These dicarbonyl compounds are versatile intermediates and have been used to prepare a range of benzopyrano isoxazoles, pyrazoles. pyrroles and pyrimidines. 3-Hydroxymethylenespiro[chroman-2. 1 '-cyclopentan]-4-one is particularly unstable to acid-base conditions. Attempts to prepare this compound resulted only in the formation of 3-(1 cyclopentenyl)chromone, arising from a bond-switch operation initiated by fragmentation of the pyranone ring in a retro-Michael reaction. Conditions suitable for extension of this reaction to other 3-hydroxymethylenechromanones have been developed, affording access to a range of hitherto inaccessible 3-alkenylchromones. The regio- and stereo-chemical outcome of the reaction has been elucidated. Some preliminary investigations of the behaviour of 3-alkenyl chromones in Diels-Alder reactions are described.","abstract_html":"The synthesis of a range of novel 2,2-disubstituted chroman-4-ones has been accomplished by the pyrrolidine catalysed condensation of a 2-hydroxyacetophenone with aldehydes and ketones. The reaction permits access to both symmetrically and unsymmetrically substituted compounds. The reaction has been extended to the preparation of a novel furochromanone, an analogue of the natural product khellin. The Schmidt reaction of 2,2-disubstituted chroman-4-ones in an acetic-sulphuric acid mixture affords 2,3,4.5-tetrahydro-1.4- benzoxazepine-5(411)--ones, resulting from alkyl migration of the iminodiszonium intermediate. Chroman-4-ones possessing a carbocation stabilising function show anomalous behaviour, the initially formed 1,4-benzoxazepinone being particularly susceptible to protolysis. 2-Methyl-2-phenylchromanone affords a 2-oxazoline as the major product, whilst 2-cyclopropyl-2- methylchromanone gives a mixture of five components which have been separated and characterised. The major products result from hydration and acetolysis of the cyclopropyl carbenium ion. Products resulting from aryl migration and anti-Markovnikov addition of acetic acid to the cyclopropane ring are also formed. Carbanions derived from chromanones have been generated and used to prepare a range of 3-hydroxymethylenechroman-4-ones. Conjugate reduction of the corresponding chromone by sodium borohydride in pyridine provides a simple entry to 3-acetyl and 3-aroyl-2-methylchromanones. These dicarbonyl compounds are versatile intermediates and have been used to prepare a range of benzopyrano isoxazoles, pyrazoles. pyrroles and pyrimidines. 3-Hydroxymethylenespiro[chroman-2. 1 '-cyclopentan]-4-one is particularly unstable to acid-base conditions. Attempts to prepare this compound resulted only in the formation of 3-(1 cyclopentenyl)chromone, arising from a bond-switch operation initiated by fragmentation of the pyranone ring in a retro-Michael reaction. Conditions suitable for extension of this reaction to other 3-hydroxymethylenechromanones have been developed, affording access to a range of hitherto inaccessible 3-alkenylchromones. The regio- and stereo-chemical outcome of the reaction has been elucidated. Some preliminary investigations of the behaviour of 3-alkenyl chromones in Diels-Alder reactions are described.","abstract_has_math":false,"creators":["Gabbutt, Christopher David"],"institution":"Lancashire Polytechnic","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1987,"date_issued":"1987-10","date_published":"1987-10","updated_at":"2026-07-24T01:36:03Z","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":["Gabbutt, Christopher David"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1987-10-01"]},{"key":"dc:date.issued","label":"Date","values":["1987-10"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["School of Chemistry"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Lancashire Polytechnic"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://knowledge.lancashire.ac.uk/id/eprint/19780/"]},{"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/19780/1/19780%20Christopher%20David%20Gabbutt%20Oct87%20Reactions%20and%20Rearrangements%20of%20Chroman-4--ones%20and%20Related%20Compounds%20Degree%20ofDoctor%20of%20Philosophy%20unpublished%20Oct87%20University%20of%20Central%20Lancashire%20chemistry%20422.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The synthesis of a range of novel 2,2-disubstituted chroman-4-ones has been accomplished by the pyrrolidine catalysed condensation of a 2-hydroxyacetophenone with aldehydes and ketones. The reaction permits access to both symmetrically and unsymmetrically substituted compounds. The reaction has been extended to the preparation of a novel furochromanone, an analogue of the natural product khellin. The Schmidt reaction of 2,2-disubstituted chroman-4-ones in an acetic-sulphuric acid mixture affords 2,3,4.5-tetrahydro-1.4- benzoxazepine-5(411)--ones, resulting from alkyl migration of the iminodiszonium intermediate. Chroman-4-ones possessing a carbocation stabilising function show anomalous behaviour, the initially formed 1,4-benzoxazepinone being particularly susceptible to protolysis. 2-Methyl-2-phenylchromanone affords a 2-oxazoline as the major product, whilst 2-cyclopropyl-2- methylchromanone gives a mixture of five components which have been separated and characterised. The major products result from hydration and acetolysis of the cyclopropyl carbenium ion. Products resulting from aryl migration and anti-Markovnikov addition of acetic acid to the cyclopropane ring are also formed. Carbanions derived from chromanones have been generated and used to prepare a range of 3-hydroxymethylenechroman-4-ones. Conjugate reduction of the corresponding chromone by sodium borohydride in pyridine provides a simple entry to 3-acetyl and 3-aroyl-2-methylchromanones. These dicarbonyl compounds are versatile intermediates and have been used to prepare a range of benzopyrano isoxazoles, pyrazoles. pyrroles and pyrimidines. 3-Hydroxymethylenespiro[chroman-2. 1 '-cyclopentan]-4-one is particularly unstable to acid-base conditions. Attempts to prepare this compound resulted only in the formation of 3-(1 cyclopentenyl)chromone, arising from a bond-switch operation initiated by fragmentation of the pyranone ring in a retro-Michael reaction. Conditions suitable for extension of this reaction to other 3-hydroxymethylenechromanones have been developed, affording access to a range of hitherto inaccessible 3-alkenylchromones. The regio- and stereo-chemical outcome of the reaction has been elucidated. Some preliminary investigations of the behaviour of 3-alkenyl chromones in Diels-Alder reactions are described."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Reactions and rearrangements of chroman-4-ones and related compounds"]}]}],"canonical_facts":{"dc:creator":["Gabbutt, Christopher David"],"dc:date":["1987-10-01"],"dc:date.issued":["1987-10"],"dc:description.abstract":["The synthesis of a range of novel 2,2-disubstituted chroman-4-ones has been accomplished by the pyrrolidine catalysed condensation of a 2-hydroxyacetophenone with aldehydes and ketones. The reaction permits access to both symmetrically and unsymmetrically substituted compounds. The reaction has been extended to the preparation of a novel furochromanone, an analogue of the natural product khellin. The Schmidt reaction of 2,2-disubstituted chroman-4-ones in an acetic-sulphuric acid mixture affords 2,3,4.5-tetrahydro-1.4- benzoxazepine-5(411)--ones, resulting from alkyl migration of the iminodiszonium intermediate. Chroman-4-ones possessing a carbocation stabilising function show anomalous behaviour, the initially formed 1,4-benzoxazepinone being particularly susceptible to protolysis. 2-Methyl-2-phenylchromanone affords a 2-oxazoline as the major product, whilst 2-cyclopropyl-2- methylchromanone gives a mixture of five components which have been separated and characterised. The major products result from hydration and acetolysis of the cyclopropyl carbenium ion. Products resulting from aryl migration and anti-Markovnikov addition of acetic acid to the cyclopropane ring are also formed. Carbanions derived from chromanones have been generated and used to prepare a range of 3-hydroxymethylenechroman-4-ones. Conjugate reduction of the corresponding chromone by sodium borohydride in pyridine provides a simple entry to 3-acetyl and 3-aroyl-2-methylchromanones. These dicarbonyl compounds are versatile intermediates and have been used to prepare a range of benzopyrano isoxazoles, pyrazoles. pyrroles and pyrimidines. 3-Hydroxymethylenespiro[chroman-2. 1 '-cyclopentan]-4-one is particularly unstable to acid-base conditions. Attempts to prepare this compound resulted only in the formation of 3-(1 cyclopentenyl)chromone, arising from a bond-switch operation initiated by fragmentation of the pyranone ring in a retro-Michael reaction. Conditions suitable for extension of this reaction to other 3-hydroxymethylenechromanones have been developed, affording access to a range of hitherto inaccessible 3-alkenylchromones. The regio- and stereo-chemical outcome of the reaction has been elucidated. Some preliminary investigations of the behaviour of 3-alkenyl chromones in Diels-Alder reactions are described."],"dc:format":["application/pdf"],"dc:identifier.uri":["https://knowledge.lancashire.ac.uk/id/eprint/19780/1/19780%20Christopher%20David%20Gabbutt%20Oct87%20Reactions%20and%20Rearrangements%20of%20Chroman-4--ones%20and%20Related%20Compounds%20Degree%20ofDoctor%20of%20Philosophy%20unpublished%20Oct87%20University%20of%20Central%20Lancashire%20chemistry%20422.pdf"],"dc:language":["en"],"dc:publisher.department":["School of Chemistry"],"dc:publisher.institution":["Lancashire Polytechnic"],"dc:relation.isreferencedby":["https://knowledge.lancashire.ac.uk/id/eprint/19780/"],"dc:subject":["F100 - Chemistry"],"dc:title":["Reactions and rearrangements of chroman-4-ones and related compounds"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T01:36:03Z"}