51
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Gallagher S, Hatoum F, Zientek N, Oelgemöller M. Photodecarboxylative additions of N-protected α-amino acids to N-methylphthalimide. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2010.05.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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52
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Yoshimi Y, Hayashi S, Nishikawa K, Haga Y, Maeda K, Morita T, Itou T, Okada Y, Ichinose N, Hatanaka M. Influence of solvent, electron acceptors and arenes on photochemical decarboxylation of free carboxylic acids via single electron transfer (SET). Molecules 2010; 15:2623-30. [PMID: 20428069 PMCID: PMC6257324 DOI: 10.3390/molecules15042623] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/02/2010] [Accepted: 04/07/2010] [Indexed: 11/16/2022] Open
Abstract
Single electron transfer (SET)-photochemical decarboxylation of free carboxylic acids was performed in a polar solvent using several arenes such as phenanthrene, naphthalene, 1-methylnaphthalene, biphenyl, triphenylene, and chrysene in the presence of various electron acceptors such as 1,2-, 1,3-, and 1,4-dicyanobenzenes, methyl 4-cyanobenzoate, and 1,4-dicyanonaphthalene. The decarboxylation reaction was influenced by the arenes, electron acceptors, and solvent. The best result was achieved by the photoreaction using biphenyl and 1,4-dicyanonaphthalene in aqueous acetonitrile.
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Affiliation(s)
- Yasuharu Yoshimi
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
- Author to whom correspondence should be addressed; E-Mail:
| | - Shota Hayashi
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Keisuke Nishikawa
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Yoshiki Haga
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Kousuke Maeda
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Toshio Morita
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Tatsuya Itou
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu 525-8577, Japan; E-Mail: (T.I.)
| | - Yutaka Okada
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu 525-8577, Japan; E-Mail: (T.I.)
| | - Nobuyuki Ichinose
- Department of Chemistry and Materials Technology, Kyoto Institue of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; E-Mail: (N.I.)
| | - Minoru Hatanaka
- Department of Medicinal and Organic Chemistry, School of Pharmacy, Iwate Medical University, Yahaba, Iwate 028-3694, Japan; E-Mail: (M.H.)
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53
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Studies aimed at elucidating factors involved in the control of chemoselectivity in single electron transfer promoted photoreactions of branched-polydonor substituted phthalimides. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.02.074] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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54
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Intermolecular Photocyclizations of N-(ω-Hydroxyalkyl)tetrachlorophthalimide with Alkenes Leading to Medium- and Large-Ring Heterocycles-Reaction Modes and Regio- and Stereoselectivity of the 1,n-Biradicals. Chemistry 2010; 16:2873-86. [DOI: 10.1002/chem.200902849] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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55
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Yoshimi Y, Masuda M, Mizunashi T, Nishikawa K, Maeda K, Koshida N, Itou T, Morita T, Hatanaka M. Inter- and intramolecular addition reactions of electron-deficient alkenes with alkyl radicals, generated by SET-photochemical decarboxylation of carboxylic acids, serve as a mild and efficient method for the preparation of gamma-amino acids and macrocyclic lactones. Org Lett 2009; 11:4652-5. [PMID: 19751053 DOI: 10.1021/ol9019277] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inter- and intramolecular additions of alkyl radicals, generated by SET photochemical decarboxylation reactions of free carboxylic acids, to electron-deficient alkenes take place under mild conditions as part of efficient routes for the formation of N-Boc gamma-amino acids and macrocyclic lactones.
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Affiliation(s)
- Yasuharu Yoshimi
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan.
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56
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Horvat M, Görner H, Warzecha KD, Neudörfl J, Griesbeck AG, Mlinarić-Majerski K, Basarić N. Photoinitiated domino reactions: N-(adamantyl)phthalimides and N-(adamantylalkyl)phthalimides. J Org Chem 2009; 74:8219-31. [PMID: 19874065 DOI: 10.1021/jo901753z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Phthalimides 1-6 undergo photochemical reactions upon direct irradiation as well as triplet sensitization and give rise to new products. Besides formation of the primary photoproducts, the first photochemical step initiates a subsequent thermal domino reaction or a domino sequence of a thermal and a photochemical reaction. The latter, involving two photochemical intramolecular gamma-H abstractions, was observed with phthalimides 1, 3, and 6 and delivered stereospecifically the hexacyclic benzazepine products 12, 19, and 27, respectively. The lowest triplet states of 1-6 were characterized in several solvents upon direct and acetone-sensitized excitation. The intermolecular electron transfer from triethylamine and DABCO was studied, and the radical anions were observed. Electrochemical measurements showed that intramolecular electron transfer from the adamantyl group of 1-6 to the lowest triplet state of the phthalimides is not feasible. The formation of products can be explained by intramolecular H-abstraction from the (alkyl)adamantane to the excited phthalimide, either from the excited singlet state or a hidden upper excited triplet state.
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Affiliation(s)
- Margareta Horvat
- Department of Organic Chemistry and Biochemistry, Ruder Bosković Institute, Bijenicka cesta 54, 10 000 Zagreb, Croatia
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57
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Huang X, Xu J. One-Pot Facile Synthesis of Substituted Isoindolinones via an Ugi Four-Component Condensation/Diels−Alder Cycloaddition/ Deselenization−Aromatization Sequence. J Org Chem 2009; 74:8859-61. [DOI: 10.1021/jo901628a] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xian Huang
- Department of Chemistry, Zhejiang University (Xixi Campus), Hangzhou 310028, People’s Republic of China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, People’s Republic of China
| | - Jianfeng Xu
- Department of Chemistry, Zhejiang University (Xixi Campus), Hangzhou 310028, People’s Republic of China
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58
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Borak JB, Falvey DE. A new photolabile protecting group for release of carboxylic acids by visible-light-induced direct and mediated electron transfer. J Org Chem 2009; 74:3894-9. [PMID: 19361187 DOI: 10.1021/jo900182x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new aqueous-compatible photoinduced electron transfer based photolabile protecting group has been developed for the release of carboxylic acids. The reduction potential of this group is more positive than previous systems, thereby allowing the use of sensitizers with modest oxidation potentials. Release of several carboxylic acids has been demonstrated using tris(bipyridyl)ruthenium(II) as both a direct sensitizer and a mediator for electron transfer between a good donor and the protecting group.
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Affiliation(s)
- J Brian Borak
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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59
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Jeong HC, Park KH, Park HJ, Cho DW, Yoon UC. Azomethine Yilde Forming Photoreaction of N-(Tributylstannyl)methylphthalimide. JOURNAL OF THE KOREAN CHEMICAL SOCIETY-DAEHAN HWAHAK HOE JEE 2009. [DOI: 10.5012/jkcs.2009.53.3.302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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60
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Cho DW, Lee HY, Oh SW, Choi JH, Park HJ, Mariano PS, Yoon UC. Photoaddition reactions of 1,2-diketones with silyl ketene acetals. formation of beta-hydroxy-gamma-ketoesters. J Org Chem 2008; 73:4539-47. [PMID: 18494523 DOI: 10.1021/jo800473x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photochemical reactions taking place between 1,2-diketones and silyl ketene acetals and their excited state reaction mechanisms have been explored. Irradiation of benzene, acetone, or acetonitrile solutions containing 1,2-diketones and silyl ketene acetals is observed to promote formation of 1,4-dioxenes, resulting from [4 + 2]-cycloaddition, oxetanes, arising by Paterno-Buchi processes, and beta-hydroxy-gamma-ketoesters, generated by SET-promoted Claisen-type condensation. These competitive pathways leading from the excited states of the 1,2-diketones to these products are influenced by solvent polarity and the nature of the silyl ketene acetal and 1,2-diketone. The Claisen-type condensation process, following an SET desilylation pathway and predominating when the photoreactions are carried out in the polar solvent acetonitrile, represents an efficient method to prepare a variety of diversely substituted beta-hydoxy-gamma-ketoesters.
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Affiliation(s)
- Dae Won Cho
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan, Korea
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61
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Maeda H, Tierney DL, Mariano PS, Banerjee M, Cho DW, Yoon UC. Lariat-crown ether based fluorescence sensors for heavy metal ions. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.03.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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62
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Affiliation(s)
- Norbert Hoffmann
- Laboratoire des Réactions Sélectives et Applications, UMR 6519 CNRS et Université de Reims Champagne-Ardenne, UFR Sciences, B.P. 1039, F-51687 Reims, Cedex 02, France
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63
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McGlacken G, Khan T. Formation of Carbanions Using Neutral Organic Molecules as Electron-Transfer Reagents: A Radical Concept. Angew Chem Int Ed Engl 2008; 47:1819-23. [DOI: 10.1002/anie.200704883] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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64
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McGlacken G, Khan T. Bildung von Carbanionen mit neutralen organischen Elektronentransferreagentien: ein Radikalkonzept. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200704883] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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65
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Cho DW, Choi JH, Oh SW, Quan C, Yoon UC, Wang R, Yang S, Mariano PS. Single Electron Transfer-Promoted Photocyclization Reactions of Linked Acceptor−Polydonor Systems: Effects of Chain Length and Type on the Efficiencies of Macrocyclic Ring-Forming Photoreactions of Tethered α-Silyl Ether Phthalimide Substrates. J Am Chem Soc 2008; 130:2276-84. [DOI: 10.1021/ja076846l] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dae Won Cho
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Jung Hei Choi
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Sun Wha Oh
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Chunsheng Quan
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Ung Chan Yoon
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Runtang Wang
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Shaorong Yang
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Patrick S. Mariano
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131
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66
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Sung NK, Cho DW, Choi JH, Choi KW, Yoon UC, Maeda H, Mariano PS. A Facile Approach to the Preparation of Bis-Crown Ethers Based on SET-Promoted Photomacrocyclization Reactions. J Org Chem 2007; 72:8831-7. [DOI: 10.1021/jo701770x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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67
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Cho DW, Fujitsuka M, Choi KH, Park MJ, Yoon UC, Majima T. Intramolecular exciplex and intermolecular excimer formation of 1,8-naphthalimide-linker-phenothiazine dyads. J Phys Chem B 2007; 110:4576-82. [PMID: 16526687 DOI: 10.1021/jp056078p] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Steady-state fluorescence spectra were measured for 1,8-naphthahlimide-linker-phenothiazine dyads (NI-L-PTZ, where L = octamethylenyl ((CH2)8) and 3,6,9-trioxaundecyl ((CH2CH2O)3C2H4)), NI-C8-PTZ and NI-O-PTZ, as well as the NI derivatives substituted on the nitrogen atom with various linker groups without PTZ as the reference NI molecule in n-hexane. Normal fluorescence peaks were observed at 367-369 nm in all NI molecules together with a broader emission around 470 nm, which is assigned to the excimer emission between the NI in the singlet excited state (1NI*) and the NI moiety of another NI molecule (1[NI/NI]*). In addition, a broad peak around 600 nm was observed only for NI-L-PTZ, which is assigned to an intramolecular exciplex emission between donor (PTZ) and acceptor (NI) moieties in the excited singlet state, 1[NI-L-NI]*. The formation of an intramolecular exciplex corresponds to the existence of a conformer with a weak face-to-face interaction between the NI and PTZ moieties in the excited state because of the long and flexible linkers. The excited-state dynamics of the NI molecules in n-hexane were established by means of time-resolved fluorescence spectroscopy.
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Affiliation(s)
- Dae Won Cho
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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68
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Single Electron Transfer Induced Photoaddition Reactions of Silyl Enol Ether to N-Methylphthalimide. B KOREAN CHEM SOC 2007. [DOI: 10.5012/bkcs.2007.28.4.629] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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69
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The Synthetic Potential of SET Photochemistry of Silicon-Substituted Polydonor-Linked Phthalimides. B KOREAN CHEM SOC 2006. [DOI: 10.5012/bkcs.2006.27.8.1099] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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70
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Cho DW, Fujitsuka M, Sugimoto A, Yoon UC, Mariano PS, Majima T. Photoinduced Electron Transfer Processes in 1,8-Naphthalimide-Linker-Phenothiazine Dyads. J Phys Chem B 2006; 110:11062-8. [PMID: 16771366 DOI: 10.1021/jp057557r] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photoinduced electron transfer (PET) processes of 1,8-naphthalimide-linker-phenothiazine (NI-L-PTZ) dyads have been investigated using the nanosecond- and picosecond-transient absorption measurements. Two kinds of linker were introduced, i.e., polymethylene-linked dyad (NI-C8-PTZ and NI-C11-PTZ) and a poly(ethyl ether)-linked one (NI-O-PTZ). The 355 nm pulsed laser excitation of NI-C8-PTZ, NI-C11-PTZ, and NI-O-PTZ in acetonitrile produced NI radical anion (NI*-) and PTZ radical cation (PTZ*+) with the absorption bands around 420 and 520 nm, respectively, through charge transfer from PTZ to NI in the singlet excited state (NI(S1)) as well as in the triplet excited states (NI(T1)) in acetonitrile. On the other hand, the charge transfer process occurred only from NI(S1) in nonpolar solvents. The rates of charge transfer and charge recombination processes largely depended on the solvent polarity and they are affected by the length of linkers and electronic coupling through polyether linker. The PET mechanism is discussed in terms of the free energy change for the charge transfer.
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Affiliation(s)
- Dae Won Cho
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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71
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A novel photochemical approach to the synthesis of naphthalene-containing lariat-type crown ethers and an evaluation of their metal cation binding and fluorescence sensing properties. J Photochem Photobiol A Chem 2005. [DOI: 10.1016/j.jphotochem.2005.05.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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72
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Hayamizu T, Maeda H, Mizuno K. Diastereoselective protonation on radical anions of electron-deficient alkenes via photoinduced electron transfer. J Org Chem 2004; 69:4997-5004. [PMID: 15255727 DOI: 10.1021/jo0496953] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Diastereoselective protonations in the photoinduced electron transfer (PET) reactions of 1,1-dicyanoethene derivatives (1a-e) by use of organosilicon compounds such as allyltrimethylsilane (2) and benzyltrimethylsilane (5) are described. Irradiation of an acetonitrile-acetic acid solution containing 4-tert-butylcyclohexylidenepropanedinitrile (1a) and an excess of 2 in the presence of phenanthrene (Phen) as a sensitizer afforded reduction and allylated products (3a, 4a) in 63:37 and 57:43 ratios in a less regioselective manner. Photoreactions of 3,3,5-trimethylcyclohexylidenepropanedinitrile (1b), 2-methylcyclohexylidenepropanedinitrile (1c), bicyclo[2.2.1]-2-heptylidenepropanedinitrile (1d), and 1,7,7-trimethylbicyclo[2.2.1]-2-heptylidenepropanedinitrile (1e) with 2 showed higher diastereoselectivity via the PET process. Similar diastereoselectivities were obtained in the Phen-sensitized photoreaction of 1a-e with 5. When 2,4,6-trimethylpyridinium tosylate (7) was used as a proton source in place of acetic acid, the product ratios were substantially changed in several cases. From these results, steric and torsional effects have been postulated as important factors for the control of the diastereoselectivity in these PET reactions.
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Affiliation(s)
- Tomoo Hayamizu
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
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73
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Yoon UC, Kwon HC, Hyung TG, Choi KH, Oh SW, Yang S, Zhao Z, Mariano PS. The Photochemistry of Polydonor-Substituted Phthalimides: Curtin-Hammett-Type Control of Competing Reactions of Potentially Interconverting Zwitterionic Biradical Intermediates. J Am Chem Soc 2004; 126:1110-24. [PMID: 14746480 DOI: 10.1021/ja0305712] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The results of studies designed to obtain information about the factors that control the chemical efficiencies/regioselectivities and quantum yields of single electron transfer (SET)-promoted reactions of acceptor-polydonor systems are reported. Photochemical and photophysical investigations were carried out with bis-donor tethered phthalimides and naphthalimides of general structure N-phthalimido- and N-naphthalimido-CH2CH2-D-CH2CH2-NMsCH2-E (E = SiMe3 or CO2NBu4 and D = NMs, O, S, and NMe). These substrates contain common terminal donor groups (NMsCH2SiMe3 or NMsCH2CO2NBu4) that have known oxidation potentials and cation radical fragmentation rates. Oxidation potentials and fragmentation rates at the other donor site in each of these substrates are varied by incorporating different heteroatoms and/or substituents. Photoproduct distribution, reaction quantum yield, and fluorescence quantum yield measurements were made. The results show that photocyclization reactions of alpha-trimethylsilylmethansulfonamide (E = SiMe3)- and alpha-carboxymethansulfonamide (E = CO2NBu4)-terminated phthalimides and naphthalimides that contain internal sulfonamide, ether, and thioether donor sites (D = NMs, O, or S) are chemically efficient (80-100%) and that they take place exclusively by a pathway involving sequential photoinduced SET (zwitterionic biradical desilylation or decarboxylation) biradical cyclization. In contrast, photoreactions of alpha-trimethylsilylmethansulfonamide- and alpha-carboxymethansulfonamide-terminated phthalimides and naphthalimides that that contain an internal tertiary amine donor site (D = NMe) are chemically inefficient and follow a pathway involving alpha-deprotonation at the tertiary amine radical cation center in intermediate, iminium radical-containing, zwitterionic biradicals. In addition, the quantum efficiencies for photoreactions of alpha-trimethylsilylmethansulfonamide- and alpha-carboxymethansulfonamide-terminated phthalimides are dependent on the nature of the internal donor (eg., phi = 0.12 for D = NMs, E = SiMe3; phi = 0.02 for D = S, E = SiMe3; phi = 0.04 for D = NMe, E = SiMe3). The results of this effort are discussed in terms of how the relative energies of interconverting zwitterionic biradical intermediates and the energy barriers for their alpha-heterolytic fragmentation reactions influence the chemical yields and quantum efficiencies of SET promoted photocyclization reactions of acceptor-polydonor substrates.
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Affiliation(s)
- Ung Chan Yoon
- Department of Chemistry and the Institute for Functional Materials, Pusan National University, Pusan 609-735, Korea
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