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Article: Photoreactions of 3-Diazo-3H-benzofuran-2-one; Dimerization and Hydrolysis of Its Primary Photoproduct, A Quinonoid Cumulenone: A Study by Time-Resolved Optical and Infrared Spectroscopy
Title | Photoreactions of 3-Diazo-3H-benzofuran-2-one; Dimerization and Hydrolysis of Its Primary Photoproduct, A Quinonoid Cumulenone: A Study by Time-Resolved Optical and Infrared Spectroscopy |
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Authors | |
Issue Date | 2003 |
Publisher | American Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.html |
Citation | Journal Of The American Chemical Society, 2003, v. 125 n. 42, p. 12872-12880 How to Cite? |
Abstract | Light-induced deazotization of 3-diazo-3H-benzofuran-2-one (1) in solution is accompanied by facile (CO)-O bond cleavage yielding 6-(oxoethenylidene)-2,4-cyclohexadien-1-one (3), which appears with a rise time of 28 ps. The expected Wolff-rearrangement product, 7-oxabicyclo[4.2.0]octa-1,3,5-trien-8-ylidenemethanone (4), is not formed. The efficient light-induced formation of the quinonoid cumulenone 3 opens the way to determine the reactivity of a cumulenone in solution. The reaction kinetics of 3 were monitored by nanosecond flash photolysis with optical (λ max ≈ 460 nm) as well as Raman (1526 cm -1) and IR detection (2050 cm -1). Remarkably, the reactivity of 3 is that expected from its valence isomer, the cyclic carbene 3H-benzofuran-2-one-3-ylidene, 2. In aqueous solution, acid-catalyzed addition of water forms the lactone 3-hydroxy-3H-benzofuran-2-one (5). The reaction is initiated by protonation of the cumulenone on its β-carbon atom. In hexane, cumulenone 3 dimerizes to isoxindigo ((E)-[3,3′ ]bibenzofuranylidene-2,2′-dione, 7), coumestan (6H-benzofuro[3,2-c][1]benzopyran-6-one, 8), and a small amount of dibenzonaphthyrone ([1]benzopyrano[4,3-][1]benzopyran-5,11-dione, 9) at a nearly diffusion-controlled rate. Ab initio calculations (G3) are consistent with the observed data. Carbene 2 is predicted to have a singlet ground state, which undergoes very facile, strongly exothermic (irreversible) ring opening to the cumulenone 3. The calculated barrier to formation of 4 (Wolff-rearrangement) is prohibitive. DFT calculations indicate that protonation of 3 on the β-carbon is accompanied by cyclization to the protonated carbene 2H +, and that dimerization of 3 to 7 and 9 takes place in a single step with negligible activation energy. |
Persistent Identifier | http://hdl.handle.net/10722/70432 |
ISSN | 2023 Impact Factor: 14.4 2023 SCImago Journal Rankings: 5.489 |
ISI Accession Number ID | |
References |
DC Field | Value | Language |
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dc.contributor.author | Chiang, Y | en_HK |
dc.contributor.author | Gaplovsky, M | en_HK |
dc.contributor.author | Kresge, AJ | en_HK |
dc.contributor.author | Leung, KH | en_HK |
dc.contributor.author | Ley, C | en_HK |
dc.contributor.author | Mac, M | en_HK |
dc.contributor.author | Persy, G | en_HK |
dc.contributor.author | Phillips, DL | en_HK |
dc.contributor.author | Popik, VV | en_HK |
dc.contributor.author | Rödig, C | en_HK |
dc.contributor.author | Wirz, J | en_HK |
dc.contributor.author | Zhu, Y | en_HK |
dc.date.accessioned | 2010-09-06T06:22:49Z | - |
dc.date.available | 2010-09-06T06:22:49Z | - |
dc.date.issued | 2003 | en_HK |
dc.identifier.citation | Journal Of The American Chemical Society, 2003, v. 125 n. 42, p. 12872-12880 | en_HK |
dc.identifier.issn | 0002-7863 | en_HK |
dc.identifier.uri | http://hdl.handle.net/10722/70432 | - |
dc.description.abstract | Light-induced deazotization of 3-diazo-3H-benzofuran-2-one (1) in solution is accompanied by facile (CO)-O bond cleavage yielding 6-(oxoethenylidene)-2,4-cyclohexadien-1-one (3), which appears with a rise time of 28 ps. The expected Wolff-rearrangement product, 7-oxabicyclo[4.2.0]octa-1,3,5-trien-8-ylidenemethanone (4), is not formed. The efficient light-induced formation of the quinonoid cumulenone 3 opens the way to determine the reactivity of a cumulenone in solution. The reaction kinetics of 3 were monitored by nanosecond flash photolysis with optical (λ max ≈ 460 nm) as well as Raman (1526 cm -1) and IR detection (2050 cm -1). Remarkably, the reactivity of 3 is that expected from its valence isomer, the cyclic carbene 3H-benzofuran-2-one-3-ylidene, 2. In aqueous solution, acid-catalyzed addition of water forms the lactone 3-hydroxy-3H-benzofuran-2-one (5). The reaction is initiated by protonation of the cumulenone on its β-carbon atom. In hexane, cumulenone 3 dimerizes to isoxindigo ((E)-[3,3′ ]bibenzofuranylidene-2,2′-dione, 7), coumestan (6H-benzofuro[3,2-c][1]benzopyran-6-one, 8), and a small amount of dibenzonaphthyrone ([1]benzopyrano[4,3-][1]benzopyran-5,11-dione, 9) at a nearly diffusion-controlled rate. Ab initio calculations (G3) are consistent with the observed data. Carbene 2 is predicted to have a singlet ground state, which undergoes very facile, strongly exothermic (irreversible) ring opening to the cumulenone 3. The calculated barrier to formation of 4 (Wolff-rearrangement) is prohibitive. DFT calculations indicate that protonation of 3 on the β-carbon is accompanied by cyclization to the protonated carbene 2H +, and that dimerization of 3 to 7 and 9 takes place in a single step with negligible activation energy. | en_HK |
dc.language | eng | en_HK |
dc.publisher | American Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.html | en_HK |
dc.relation.ispartof | Journal of the American Chemical Society | en_HK |
dc.title | Photoreactions of 3-Diazo-3H-benzofuran-2-one; Dimerization and Hydrolysis of Its Primary Photoproduct, A Quinonoid Cumulenone: A Study by Time-Resolved Optical and Infrared Spectroscopy | en_HK |
dc.type | Article | en_HK |
dc.identifier.openurl | http://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0002-7863&volume=125&spage=12872&epage=12880&date=2003&atitle=Photoreactions+of+3-Diazo-3H-benzofuran-2-one;+dimerization+and+hydrolysis+of+its+primary+photoproduct,+a+quinonoid+cumulenone:+a+study+by+time-resolved+optical+and+infrared+spectroscopy++ | en_HK |
dc.identifier.email | Phillips, DL:phillips@hku.hk | en_HK |
dc.identifier.authority | Phillips, DL=rp00770 | en_HK |
dc.description.nature | link_to_subscribed_fulltext | - |
dc.identifier.doi | 10.1021/ja0365476 | en_HK |
dc.identifier.scopus | eid_2-s2.0-10744225801 | en_HK |
dc.identifier.hkuros | 92461 | en_HK |
dc.relation.references | http://www.scopus.com/mlt/select.url?eid=2-s2.0-10744225801&selection=ref&src=s&origin=recordpage | en_HK |
dc.identifier.volume | 125 | en_HK |
dc.identifier.issue | 42 | en_HK |
dc.identifier.spage | 12872 | en_HK |
dc.identifier.epage | 12880 | en_HK |
dc.identifier.isi | WOS:000185990300048 | - |
dc.publisher.place | United States | en_HK |
dc.identifier.scopusauthorid | Chiang, Y=7201593533 | en_HK |
dc.identifier.scopusauthorid | Gaplovsky, M=6507254427 | en_HK |
dc.identifier.scopusauthorid | Kresge, AJ=7005589084 | en_HK |
dc.identifier.scopusauthorid | Leung, KH=7401860609 | en_HK |
dc.identifier.scopusauthorid | Ley, C=7005238686 | en_HK |
dc.identifier.scopusauthorid | Mac, M=7003388142 | en_HK |
dc.identifier.scopusauthorid | Persy, G=6603255350 | en_HK |
dc.identifier.scopusauthorid | Phillips, DL=7404519365 | en_HK |
dc.identifier.scopusauthorid | Popik, VV=7003701709 | en_HK |
dc.identifier.scopusauthorid | Rödig, C=55194084900 | en_HK |
dc.identifier.scopusauthorid | Wirz, J=34573960100 | en_HK |
dc.identifier.scopusauthorid | Zhu, Y=7406073580 | en_HK |
dc.identifier.issnl | 0002-7863 | - |