{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/70230"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/70230","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Geometrical Analogues of Purine Substrates (5-Methyladenine, Pyrolysis, Diazabiphenylene)","abstract":"Synthetic approaches are developed to cyclobutadienopurines and lin-benzocyclobutadienopurines, new extended purine analogues, by means of flash vacuum pyrolysis of suitable condensed pyridazine precursors. As a model for the cyclobutadienopurine ring system, benzo{3,4}cyclobutadieno{1,2-d}imidazole was prepared by thermal extrusion of dinitrogen. As expected of biphenylene analogues with increased electron density in the four-membered ring, the benzocyclobutadienoimidazole underwent extensive decomposition.","abstract_html":"Synthetic approaches are developed to cyclobutadienopurines and lin-benzocyclobutadienopurines, new extended purine analogues, by means of flash vacuum pyrolysis of suitable condensed pyridazine precursors. As a model for the cyclobutadienopurine ring system, benzo{3,4}cyclobutadieno{1,2-d}imidazole was prepared by thermal extrusion of dinitrogen. As expected of biphenylene analogues with increased electron density in the four-membered ring, the benzocyclobutadienoimidazole underwent extensive decomposition.","abstract_has_math":false,"creators":["Bakthavachalam, Venkatesalu"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-12-15T23:18:00Z","date_published":"2014-12-15T23:18:00Z","updated_at":"2026-07-22T22:26:02Z","subjects":["Chemistry, Organic"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI8409744"],"render_values":[{"text":"(UMI)AAI8409744","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/70230","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Bakthavachalam, Venkatesalu"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-12-15T23:18:00Z","10000-01-01","1984"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Chemistry, Organic"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/70230","(UMI)AAI8409744"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Synthetic approaches are developed to cyclobutadienopurines and lin-benzocyclobutadienopurines, new extended purine analogues, by means of flash vacuum pyrolysis of suitable condensed pyridazine precursors. As a model for the cyclobutadienopurine ring system, benzo{3,4}cyclobutadieno{1,2-d}imidazole was prepared by thermal extrusion of dinitrogen. As expected of biphenylene analogues with increased electron density in the four-membered ring, the benzocyclobutadienoimidazole underwent extensive decomposition.","The first examples of the 1,3-diazabiphenylene ring system were synthesized by pyrolysis of pyrimidocinnoline precursors as preludes to the synthesis of lin-bcb-purines. A peculiar transformation of the 1,3-diazabiphenylene ring system into the isoquinoline ring system was observed when 4-chloro-1,3-diazabiphenylene was treated with sodium methoxide in methanol. The intermediacy of a benzodiazocine between two electrocyclic reactions was proposed for this transformation.","Several pyrimido{5,6-i}imidazo{4,5-g}cinnolines were prepared to serve as precursors for the synthesis of lin-bcb-purines in pyrolysis reactions. Chloro, methoxy, or trimethylsilyloxy precursors with N-benzyl and N-trimethylsilyl protecting groups failed to produce lin-bcb-purines on attempted pyrolysis. The unsubstituted precursor, pyrimido{5,6-i}imidazo{4,5-g}cinnoline, however, provided imidazo{4,5-h}-1,3-diazabiphenylene, the new purine analogue lin-bcb-purine.","Semiempirical molecular orbital calculations based on a MINDO/3 program were performed on 5-methyl-5H-adenine and its proposed intermediacy in a translocative rearrangement. The results revealed the relative instability of 5-methyladenine with respect to the stability of the final rearrangement product 4-amino-8-methylimidazo{1,5-a}triazine. The calculations also provided insight into the probable loci of bond-breaking and into the structures of the potential intermediates in the ring opening of 5-methyladenine.","Made available in DSpace on 2014-12-15T23:18:00Z (GMT). No. of bitstreams: 1 8409744.pdf: 2297642 bytes, checksum: 83ee7240f16ef7c13fb9452a992970cc (MD5) Previous issue date: 1984","Embargo set by: Seth Robbins for item 70396 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","85 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984."]},{"key":"dc:title","label":"Title","values":["Geometrical Analogues of Purine Substrates (5-Methyladenine, Pyrolysis, Diazabiphenylene)"]}]}],"canonical_facts":{"dc:creator":["Bakthavachalam, Venkatesalu"],"dc:date":["2014-12-15T23:18:00Z","10000-01-01","1984"],"dc:description":["Synthetic approaches are developed to cyclobutadienopurines and lin-benzocyclobutadienopurines, new extended purine analogues, by means of flash vacuum pyrolysis of suitable condensed pyridazine precursors. As a model for the cyclobutadienopurine ring system, benzo{3,4}cyclobutadieno{1,2-d}imidazole was prepared by thermal extrusion of dinitrogen. As expected of biphenylene analogues with increased electron density in the four-membered ring, the benzocyclobutadienoimidazole underwent extensive decomposition.","The first examples of the 1,3-diazabiphenylene ring system were synthesized by pyrolysis of pyrimidocinnoline precursors as preludes to the synthesis of lin-bcb-purines. A peculiar transformation of the 1,3-diazabiphenylene ring system into the isoquinoline ring system was observed when 4-chloro-1,3-diazabiphenylene was treated with sodium methoxide in methanol. The intermediacy of a benzodiazocine between two electrocyclic reactions was proposed for this transformation.","Several pyrimido{5,6-i}imidazo{4,5-g}cinnolines were prepared to serve as precursors for the synthesis of lin-bcb-purines in pyrolysis reactions. Chloro, methoxy, or trimethylsilyloxy precursors with N-benzyl and N-trimethylsilyl protecting groups failed to produce lin-bcb-purines on attempted pyrolysis. The unsubstituted precursor, pyrimido{5,6-i}imidazo{4,5-g}cinnoline, however, provided imidazo{4,5-h}-1,3-diazabiphenylene, the new purine analogue lin-bcb-purine.","Semiempirical molecular orbital calculations based on a MINDO/3 program were performed on 5-methyl-5H-adenine and its proposed intermediacy in a translocative rearrangement. The results revealed the relative instability of 5-methyladenine with respect to the stability of the final rearrangement product 4-amino-8-methylimidazo{1,5-a}triazine. The calculations also provided insight into the probable loci of bond-breaking and into the structures of the potential intermediates in the ring opening of 5-methyladenine.","Made available in DSpace on 2014-12-15T23:18:00Z (GMT). No. of bitstreams: 1 8409744.pdf: 2297642 bytes, checksum: 83ee7240f16ef7c13fb9452a992970cc (MD5) Previous issue date: 1984","Embargo set by: Seth Robbins for item 70396 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","85 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984."],"dc:identifier":["http://hdl.handle.net/2142/70230","(UMI)AAI8409744"],"dc:subject":["Chemistry, Organic"],"dc:title":["Geometrical Analogues of Purine Substrates (5-Methyladenine, Pyrolysis, Diazabiphenylene)"],"dc:type":["text"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:02Z"}