{"id":{"repo_id":"cent-lancashire","oai_identifier":"oai:clok.uclan.ac.uk:20143"},"canonical_url":"https://search.dev.ndltd.org/etd/cent-lancashire/oai:clok.uclan.ac.uk:20143","repository":{"repo_id":"cent-lancashire","name":"University of Central Lancashire","base_url":"https://clok.uclan.ac.uk/cgi/oai2"},"display":{"title":"Investigations of benzothienopyrans and related compounds","abstract":"The synthesis of isomeric benzothienopyran-4-ones has been investigated. 2-Methoxybenzo[b}thiophene has been used to prepare 2,2-dimethyl-2,3-dihydrobenzothieno[2,3-b] pyran-4-one via acylation with 3,3-dimethylacryloyl chloride. 2-Acetyl-3-hydroxybenzo[bjthiophene, readily available in a single step from thiosalicylic acid, has been used to obtain a range of 2,2-disubstituted 2,3-dihydrobenzothieno[3,2-bjpyran-4-ones by direct condensation with an aliphatic or alicyclic ketone under pyrrolidine catalysis. A greatly improved route was developed which relied upon formation of the dianion of 2-acetyl-3-hydroxybenzo[b]thiophene. The dianion was intercepted with a wide range of ketones to give the corresponding /3-hydroxy ketones. Cyclisation to the benzothieno[3,2-b]pyranones results on treatment with acid. Reaction of the dianion with tetraphenylcyclopentadienone gave a fulvene derivative that was resistant to cyclisation. With 2,5-diethyl-3,4-diphenylcyclopentadienone, stereospecific 1,6-addition occurred. The structure of the product was elucidated using X-ray crystallography. Reduction of the benzothienopyranones follows the expected course, as does their reaction with Grignard reagents. However, with PhMgBr, 2,2-diphenyl-3-methyl-2,3-dihydrobenzothieno[3,2-b]pyran-4-one underwent a novel reaction sequence to give a 3-phenylbenzo[b]thiophene derivative, the structure of which was established by X-ray crystallography. The benzothienopyranones are readily cleaved by alkoxide under mild conditions. Reactions of the resulting 2-alkenoyl-3- hydroxybenzo[b] thiophenes with hydrazine derivatives afford novel pyrazolidines. The preparation of 2,2-disubstituted benzothieno[2,3-b]- and [3,2-b]- pyrans has been investigated. The [2,3-b] isomers exist preferentially as their dienone valence tautomers. In the latter series, the pyran form predominates and the compounds exhibit photochromism providing that an aryl substituent is present at C-4. Attempts to effect acid catalysed dehydration of the benzothieno[3,2-b]pyran-4-ols failed. However, treatment with N,N-dimethylcarbamyl chloride effects a novel acylative ring cleavage to give 2-(alka- 1 ,3-dien- I -yl)-3(dimethylaminocarbamyloxy) benzo[b]thiophenes. Electrocyclisation of these carbamates has been accomplished and developed as a new approach to dibenzothiophenes and fused-ring derivatives. The synthesis of chroman-4-ones possessing C-2 spiro-annulated 9-(9Hfluorene), 1 '-indane, 3'-(2,3-dihydrobenzofuran), and 3'-(2,3-dihydrobenzo-[b]thiophene) units has been accomplished and their oxidative ring expansion by organoiodine(Ill) reagents e.g. PhI(OH)OTs has been investigated. The indane derivative afforded 1 2H-benzo[a]xanthen- 12-one and its 5,6-dihydro derivative together with 5,6-dihydro-7H-benzo[c]xanthen-7-one, whilst the benzofuran affords a ring cleaved product together with the tetracyclic rotenoid core, rotoxen-12(611)-one. Conjugate reduction of these systems provided both the cis and trans tetrahydrobenzoxanthones, and the trans-B/C fused rotenoid, respectively. Treatment of the spiro benzo[b]thiophene derivative with PhI(OH)OTs in methanol initiated a novel Pummerer-type reaction and rearrangement products were not observed.","abstract_html":"The synthesis of isomeric benzothienopyran-4-ones has been investigated. 2-Methoxybenzo[b}thiophene has been used to prepare 2,2-dimethyl-2,3-dihydrobenzothieno[2,3-b] pyran-4-one via acylation with 3,3-dimethylacryloyl chloride. 2-Acetyl-3-hydroxybenzo[bjthiophene, readily available in a single step from thiosalicylic acid, has been used to obtain a range of 2,2-disubstituted 2,3-dihydrobenzothieno[3,2-bjpyran-4-ones by direct condensation with an aliphatic or alicyclic ketone under pyrrolidine catalysis. A greatly improved route was developed which relied upon formation of the dianion of 2-acetyl-3-hydroxybenzo[b]thiophene. The dianion was intercepted with a wide range of ketones to give the corresponding /3-hydroxy ketones. Cyclisation to the benzothieno[3,2-b]pyranones results on treatment with acid. Reaction of the dianion with tetraphenylcyclopentadienone gave a fulvene derivative that was resistant to cyclisation. With 2,5-diethyl-3,4-diphenylcyclopentadienone, stereospecific 1,6-addition occurred. The structure of the product was elucidated using X-ray crystallography. Reduction of the benzothienopyranones follows the expected course, as does their reaction with Grignard reagents. However, with PhMgBr, 2,2-diphenyl-3-methyl-2,3-dihydrobenzothieno[3,2-b]pyran-4-one underwent a novel reaction sequence to give a 3-phenylbenzo[b]thiophene derivative, the structure of which was established by X-ray crystallography. The benzothienopyranones are readily cleaved by alkoxide under mild conditions. Reactions of the resulting 2-alkenoyl-3- hydroxybenzo[b] thiophenes with hydrazine derivatives afford novel pyrazolidines. The preparation of 2,2-disubstituted benzothieno[2,3-b]- and [3,2-b]- pyrans has been investigated. The [2,3-b] isomers exist preferentially as their dienone valence tautomers. In the latter series, the pyran form predominates and the compounds exhibit photochromism providing that an aryl substituent is present at C-4. Attempts to effect acid catalysed dehydration of the benzothieno[3,2-b]pyran-4-ols failed. However, treatment with N,N-dimethylcarbamyl chloride effects a novel acylative ring cleavage to give 2-(alka- 1 ,3-dien- I -yl)-3(dimethylaminocarbamyloxy) benzo[b]thiophenes. Electrocyclisation of these carbamates has been accomplished and developed as a new approach to dibenzothiophenes and fused-ring derivatives. The synthesis of chroman-4-ones possessing C-2 spiro-annulated 9-(9Hfluorene), 1 '-indane, 3'-(2,3-dihydrobenzofuran), and 3'-(2,3-dihydrobenzo-[b]thiophene) units has been accomplished and their oxidative ring expansion by organoiodine(Ill) reagents e.g. PhI(OH)OTs has been investigated. The indane derivative afforded 1 2H-benzo[a]xanthen- 12-one and its 5,6-dihydro derivative together with 5,6-dihydro-7H-benzo[c]xanthen-7-one, whilst the benzofuran affords a ring cleaved product together with the tetracyclic rotenoid core, rotoxen-12(611)-one. Conjugate reduction of these systems provided both the cis and trans tetrahydrobenzoxanthones, and the trans-B/C fused rotenoid, respectively. Treatment of the spiro benzo[b]thiophene derivative with PhI(OH)OTs in methanol initiated a novel Pummerer-type reaction and rearrangement products were not observed.","abstract_has_math":false,"creators":["Thomas, Jean-Luc"],"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":1999,"date_issued":"1999-04","date_published":"1999-04","updated_at":"2026-07-24T01:36:06Z","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":["Thomas, Jean-Luc"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1999-04-01"]},{"key":"dc:date.issued","label":"Date","values":["1999-04"]},{"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/20143/"]},{"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/20143/1/20143%20Jean-Luc%20Thomas%20Apr99%20investigations%20of%20benzothienopyrans%20%20related%20compounds%20Degree%20of%20%20Doctor%20of%20philosophy%20unpublished%20Apr99%20University%20of%20Central%20Lancashire%20Chemistry%20345.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The synthesis of isomeric benzothienopyran-4-ones has been investigated. 2-Methoxybenzo[b}thiophene has been used to prepare 2,2-dimethyl-2,3-dihydrobenzothieno[2,3-b] pyran-4-one via acylation with 3,3-dimethylacryloyl chloride. 2-Acetyl-3-hydroxybenzo[bjthiophene, readily available in a single step from thiosalicylic acid, has been used to obtain a range of 2,2-disubstituted 2,3-dihydrobenzothieno[3,2-bjpyran-4-ones by direct condensation with an aliphatic or alicyclic ketone under pyrrolidine catalysis. A greatly improved route was developed which relied upon formation of the dianion of 2-acetyl-3-hydroxybenzo[b]thiophene. The dianion was intercepted with a wide range of ketones to give the corresponding /3-hydroxy ketones. Cyclisation to the benzothieno[3,2-b]pyranones results on treatment with acid. Reaction of the dianion with tetraphenylcyclopentadienone gave a fulvene derivative that was resistant to cyclisation. With 2,5-diethyl-3,4-diphenylcyclopentadienone, stereospecific 1,6-addition occurred. The structure of the product was elucidated using X-ray crystallography. Reduction of the benzothienopyranones follows the expected course, as does their reaction with Grignard reagents. However, with PhMgBr, 2,2-diphenyl-3-methyl-2,3-dihydrobenzothieno[3,2-b]pyran-4-one underwent a novel reaction sequence to give a 3-phenylbenzo[b]thiophene derivative, the structure of which was established by X-ray crystallography. The benzothienopyranones are readily cleaved by alkoxide under mild conditions. Reactions of the resulting 2-alkenoyl-3- hydroxybenzo[b] thiophenes with hydrazine derivatives afford novel pyrazolidines. The preparation of 2,2-disubstituted benzothieno[2,3-b]- and [3,2-b]- pyrans has been investigated. The [2,3-b] isomers exist preferentially as their dienone valence tautomers. In the latter series, the pyran form predominates and the compounds exhibit photochromism providing that an aryl substituent is present at C-4. Attempts to effect acid catalysed dehydration of the benzothieno[3,2-b]pyran-4-ols failed. However, treatment with N,N-dimethylcarbamyl chloride effects a novel acylative ring cleavage to give 2-(alka- 1 ,3-dien- I -yl)-3(dimethylaminocarbamyloxy) benzo[b]thiophenes. Electrocyclisation of these carbamates has been accomplished and developed as a new approach to dibenzothiophenes and fused-ring derivatives. The synthesis of chroman-4-ones possessing C-2 spiro-annulated 9-(9Hfluorene), 1 '-indane, 3'-(2,3-dihydrobenzofuran), and 3'-(2,3-dihydrobenzo-[b]thiophene) units has been accomplished and their oxidative ring expansion by organoiodine(Ill) reagents e.g. PhI(OH)OTs has been investigated. The indane derivative afforded 1 2H-benzo[a]xanthen- 12-one and its 5,6-dihydro derivative together with 5,6-dihydro-7H-benzo[c]xanthen-7-one, whilst the benzofuran affords a ring cleaved product together with the tetracyclic rotenoid core, rotoxen-12(611)-one. Conjugate reduction of these systems provided both the cis and trans tetrahydrobenzoxanthones, and the trans-B/C fused rotenoid, respectively. Treatment of the spiro benzo[b]thiophene derivative with PhI(OH)OTs in methanol initiated a novel Pummerer-type reaction and rearrangement products were not observed."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Investigations of benzothienopyrans and related compounds"]}]}],"canonical_facts":{"dc:creator":["Thomas, Jean-Luc"],"dc:date":["1999-04-01"],"dc:date.issued":["1999-04"],"dc:description.abstract":["The synthesis of isomeric benzothienopyran-4-ones has been investigated. 2-Methoxybenzo[b}thiophene has been used to prepare 2,2-dimethyl-2,3-dihydrobenzothieno[2,3-b] pyran-4-one via acylation with 3,3-dimethylacryloyl chloride. 2-Acetyl-3-hydroxybenzo[bjthiophene, readily available in a single step from thiosalicylic acid, has been used to obtain a range of 2,2-disubstituted 2,3-dihydrobenzothieno[3,2-bjpyran-4-ones by direct condensation with an aliphatic or alicyclic ketone under pyrrolidine catalysis. A greatly improved route was developed which relied upon formation of the dianion of 2-acetyl-3-hydroxybenzo[b]thiophene. The dianion was intercepted with a wide range of ketones to give the corresponding /3-hydroxy ketones. Cyclisation to the benzothieno[3,2-b]pyranones results on treatment with acid. Reaction of the dianion with tetraphenylcyclopentadienone gave a fulvene derivative that was resistant to cyclisation. With 2,5-diethyl-3,4-diphenylcyclopentadienone, stereospecific 1,6-addition occurred. The structure of the product was elucidated using X-ray crystallography. Reduction of the benzothienopyranones follows the expected course, as does their reaction with Grignard reagents. However, with PhMgBr, 2,2-diphenyl-3-methyl-2,3-dihydrobenzothieno[3,2-b]pyran-4-one underwent a novel reaction sequence to give a 3-phenylbenzo[b]thiophene derivative, the structure of which was established by X-ray crystallography. The benzothienopyranones are readily cleaved by alkoxide under mild conditions. Reactions of the resulting 2-alkenoyl-3- hydroxybenzo[b] thiophenes with hydrazine derivatives afford novel pyrazolidines. The preparation of 2,2-disubstituted benzothieno[2,3-b]- and [3,2-b]- pyrans has been investigated. The [2,3-b] isomers exist preferentially as their dienone valence tautomers. In the latter series, the pyran form predominates and the compounds exhibit photochromism providing that an aryl substituent is present at C-4. Attempts to effect acid catalysed dehydration of the benzothieno[3,2-b]pyran-4-ols failed. However, treatment with N,N-dimethylcarbamyl chloride effects a novel acylative ring cleavage to give 2-(alka- 1 ,3-dien- I -yl)-3(dimethylaminocarbamyloxy) benzo[b]thiophenes. Electrocyclisation of these carbamates has been accomplished and developed as a new approach to dibenzothiophenes and fused-ring derivatives. The synthesis of chroman-4-ones possessing C-2 spiro-annulated 9-(9Hfluorene), 1 '-indane, 3'-(2,3-dihydrobenzofuran), and 3'-(2,3-dihydrobenzo-[b]thiophene) units has been accomplished and their oxidative ring expansion by organoiodine(Ill) reagents e.g. PhI(OH)OTs has been investigated. The indane derivative afforded 1 2H-benzo[a]xanthen- 12-one and its 5,6-dihydro derivative together with 5,6-dihydro-7H-benzo[c]xanthen-7-one, whilst the benzofuran affords a ring cleaved product together with the tetracyclic rotenoid core, rotoxen-12(611)-one. Conjugate reduction of these systems provided both the cis and trans tetrahydrobenzoxanthones, and the trans-B/C fused rotenoid, respectively. Treatment of the spiro benzo[b]thiophene derivative with PhI(OH)OTs in methanol initiated a novel Pummerer-type reaction and rearrangement products were not observed."],"dc:format":["application/pdf"],"dc:identifier.uri":["https://knowledge.lancashire.ac.uk/id/eprint/20143/1/20143%20Jean-Luc%20Thomas%20Apr99%20investigations%20of%20benzothienopyrans%20%20related%20compounds%20Degree%20of%20%20Doctor%20of%20philosophy%20unpublished%20Apr99%20University%20of%20Central%20Lancashire%20Chemistry%20345.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/20143/"],"dc:subject":["F100 - Chemistry"],"dc:title":["Investigations of benzothienopyrans and related compounds"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T01:36:06Z"}