Photochemical Electron Transfer Mediated Addition of Naphthylamine Derivatives to Electron-Deficient Alkenes (original) (raw)
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The Journal of Organic Chemistry, 1987
Irradiation of N-methyl-1,8-naphthalimide (NMN) in the presence of a-methylstyrene (a-MS) or 1,l-diphenylethylene in methanol gives novel tetracyclic imides. The mechanism proposed involves photostimulated electron transfer from the alkene to 1,8-NMN and radical coupling addition of methanol to the resultant radical cation-radical anion pair at the 4-position of the aromatic ring to give an unisolable intermediate with an a,@-unsaturated carbonyl moiety. Absorption of a second photon by this chromophore gives rise to the final product. The predicted regiochemistry and stereochemistry of the reaction were established by using pentadeuterio-a-methylstyrene (16), thus providing strong evidence for the mechanism. The photochemistry of aromatic imides has been the subject of extensive investigation for more than a decade.' We have studied the intermolecular and intramolecular photoaddition of alkenes to phthalimides focusing on mechanistic details2+ and have shown the usefulness of one of these reactions as the key step in the synthesis of natural product^.^ Alkene addition to excited Nmthylphthalimide (NMP) is described by four processes: (1) 27r + 2a cycloaddition between the alkene and the C(0)-N bond to give a benzazepinedione;2 (2) 27r + 27r cycloaddition between the carbonyl and the alkene to afford Paterno-Buchi adducts3 1; (3) photoredu~tion~~~J'~~ to give 2 and 3; (4) alcohol incorporation affording 4. A 3 0 &e NCH, 4 0 concerted mechanism is involved in the formation of the benzazepinedione,2 whereas the photoreduction and alco
Photochemical Reactivity of Naphthol-Naphthalimide Conjugates and Their Biological Activity
2021
Quinone methide precursors 1a–e, with different alkyl linkers between the naphthol and the naphthalimide chromophore, were synthesized. Their photophysical properties and photochemical reactivity were investigated and connected with biological activity. Upon excitation of the naphthol, Förster resonance energy transfer (FRET) to the naphthalimide takes place and the quantum yields of fluorescence are low (ΦF ≈ 10−2). Due to FRET, photodehydration of naphthols to QMs takes place inefficiently (ΦR ≈ 10−5). However, the formation of QMs can also be initiated upon excitation of naphthalimide, the lower energy chromophore, in a process that involves photoinduced electron transfer (PET) from the naphthol to the naphthalimide. Fluorescence titrations revealed that 1a and 1e form complexes with ct-DNA with moderate association constants Ka ≈ 105–106 M−1, as well as with bovine serum albumin (BSA) Ka ≈ 105 M−1 (1:1 complex). The irradiation of the complex 1e@BSA resulted in the alkylation of...
The Journal of Organic Chemistry, 2003
The fluorescent excited state of the 2-naphthoxide ion (1) is quenched by aliphatic and aromatic halides according to an electron-transfer mechanism, with generation of the corresponding alkyl and aryl radicals by a concerted or consecutive C-X bond fragmentation reaction. Whereas bromoand iodobenzene follow a concerted ET mechanism (C-X, BDE control), 1-bromonaphthalene exhibits a stepwise process (π LUMO control). The photoinduced reaction of anion 1 with 1-iodoadamantane (2) in DMSO affords substitution products on C3, C6, and C8, 1-adamantanol, 1-adamantyl 2-naphthyl ether, and adamantane (3.2, 13.2, 12.2, 2.8, 2.5, and 14.1% yields, respectively). A complex mixture is also observed in the photochemical reaction of neopentyl iodide (3) with anion 1, which renders substitution on C1, C3, C6, C8, and 2-naphthyl neopentyl ether (8.1, 1.3, 19.1, 31.1, and 2.8% yields, respectively). The absence of reaction in the dark and the inhibition of the photoinduced reaction by the presence of the radical traps di-tert-butylnitroxide (DTBN) and 1,4-cyclohexadiene are evidence of a radical chain mechanism for these substitutions. On the other hand, only coupling at C1 is achieved by the photostimulated reaction of anion 1 with iodobenzene (5), to afford 41.9% of 1-phenyl-2-naphthol and 5.4% of disubstitution product. The regiochemistry of these reactions can be ascribed to steric hindrance and activation parameters.
Tetrahedron Letters, 1993
Allylic tributyltins add to aromatic alakhydes to afford regioreversed a-a&iuct predominantly with almost complete retention of the stereochemistry of the allylic groups under photochemical conditions. The photoinduced single ekctron transfer mechanism is proposed. The addition of allyltin reagents to aldehydes has been extensively developed for the useful carbon-carbon bond construction in organic synthesis over the past decade.1 The addition reaction has been promoted by Lewis acids? heat? and high pressure.* In general, the reaction of aldehydes with the substituted allylic stamtanes under these conditions results in the products in which the allylic group is attached at the more highly substituted position (y-adduct). On the other hand, the regioreversed addition of the allylic stannanes to aldehydes to produce linear homoallylic alcohols (a&duct) has been scarcely studied.5 but the stereoselective addition with retention of the double-bond geometry of the allylic group in the tin reagents is totally unprecedented despite their gmat potential importance in organic synthesis. 6 Recently, we found that the addition maction of allyltrialkyltins to carbonyl compounds such as benzophenone, enone, and benxil could be also promoted by light7 Herein. we report that the photoinduced a-m&selective and stereospecific allylation of aromatic aldehydes using (I?)-and (Z)-allylic tributyltins. "'r sflu3 + ArcHO ' ' a 1 radduyoH I R1*h a-adduct A representative experimental procedure is given by the reaction of pcyanobenzaldehyde with (II)-2pentenylttibutykin (PBT; EIZ = 955): A N2-purged ptopionitrile solution (10 mL) of the aldehyde (52.4 mg. 0.4 mmol) and the PBT (215.6 mg, 0.6 mmol) was irradiated at-78 'C with a light (2320 nm) from a 300 W high
Journal of the American Chemical Society, 1996
Addition of alkylbenzenes with 10-methylacridinium ion (AcrH +) occurs efficiently under visible light irradiation in deaerated acetonitrile containing H 2 O to yield 9-alkyl-10-methyl-9,10-dihydroacridine selectively. On the other hand, the photochemical reaction of AcrH + with alkylbenzenes in the presence of perchloric acid in deaerated acetonitrile yields 10-methyl-9,10-dihydroacridine, accompanied by the oxygenation of alkylbenzenes to the corresponding benzyl alcohols. The photooxygenation of alkylbenzenes occurs also in the presence of oxygen, when AcrH + acts as an efficient photocatalyst. The studies on the quantum yields and fluorescence quenching of AcrH + by alkylbenzenes as well as the laser flash photolysis have revealed that the photochemical reactions of AcrH + with alkylbenzenes in both the absence and presence of oxygen proceed via photoinduced electron transfer from alkylbenzenes to the singlet excited state of AcrH + to produce alkylbenzene radical cations and 10-methylacridinyl radical (AcrH •). The competition between the deprotonation of alkylbenzene radical cations and the back electron transfer from AcrH • to the radical cations determines the limiting quantum yields. In the absence of oxygen, the coupling of the deprotonated radicals with AcrH • yields the adducts. The photoinduced hydride reduction of AcrH + in the presence of perchloric acid proceeds via the protonation of acridinyl radical produced by the photoinduced electron transfer from alkylbenzenes. In the presence of oxygen, however, the deprotonated radicals are trapped efficiently by oxygen to give the corresponding peroxyl radicals which are reduced by the back electron transfer from AcrH • to regenerate AcrH + , followed by the protonation to yield the corresponding hydroperoxide. The ratios of the deprotonation reactivity from different alkyl groups of alkylbenzene radical cations were determined from both the intra-and intermolecular competitions of the deprotonation from two alkyl groups of alkylbenzene radical cations. The reactivity of the deprotonation from alkylbenzene radical cations increases generally in the order methyl < ethyl < isopropyl. The strong stereoelectronic effects on the deprotonation from isopropyl group of alkylbenzene radical cations appear in the case of the o-methyl isomer. R-carbon to yield benzyl radical and analogs. 12-15 Such
Photoinduced energy–electron transfer studies with naphthalene diimides
Journal of Photochemistry and Photobiology A-chemistry, 2000
Seven derivatives of naphthalene diimides, synthesized, have shown similar photophysical properties. Low fluorescence quantum yields (0.002-0.006) and short fluorescence lifetimes (5-18 ps) have suggested rapid intersystem crossing processes from excited singlet state. Quenching of fluorescence emissions of aromatic donor molecules, i.e. naphthalene, phenanthrene and pyrene, at rates reaching to diffusion limits in acetonitrile (2-8×10 10 M −1 s −1 ), have proven the electron acceptor capacities of naphthalene diimides. Photooxydation of styrene to benzaldehyde, in presence of naphthalene diimide (NDI) molecule, is found to occur at similar rates with respect to perylene diimides. Addition of ferric and cupric ions to NDI, have enhanced the formation rate of benzaldehyde by about two-fold. Photooxidation of ␣-terpinene with naphthalene diimide, produced only p-cymene, no endoperoxide adduct was identified. Naphthalene diimides appear to produce no singlet oxygen, and photooxidation probably occurs on radical chain reactions of super oxide anion radical. But the electron transfer electron via excited triplet or singlet state, remains to be unclear.
The Journal of Organic Chemistry, 2006
Table of Contents Experimental Section Experimental procedure for amination of 1-chloronaphthalene using secondary cyclic amines S4 Experimental procedure for amination of 1-chloronaphthalene using anilines S6 Experimental procedure for the TiCl 4-mediated oxidative coupling of naphthylamines S9 Electrochemical Section Calculation of the number of electrons exchanged, n, during the electrochemical oxidation of naphthidines, as determined by chronoamperometry S14 Dependence of anodic and cathodic peak potentials on scan rate (log scale) at different concentrations of naphthidine 2g S16 Voltammetric in situ monitoring of the electrolysis of derivative 2g S17 UV-visible Spectra UV-visible spectra of the stepwise chemical oxidation of compounds 2c-f and 2h S19 Theoretical Section Computational details S24 Additional informations on the naphthidine properties Ionization energies S26 EPR spectra S26 References S27 S3 Experimental Section All reactions were carried out using standard Schlenk techniques under an atmosphere of nitrogen. GC and GC-MS analyses were conducted with an Optima 5 column. All quantifications of reaction constituents were achieved by gas chromatography using a known quantity of decane as reference standard. Melting points were taken on a Tottoli apparatus and were uncorrected. The 1 H, 19 F and 13 C NMR spectra were recorded at 400.13, 235.0 and 100.40 MHz using CDCl 3 as solvent. All 13 C, and 19 F NMR spectra are proton decoupled. IR spectra were recorded using NaCl cells or mixture of compounds/KBr. Compounds previously described were characterized by 1 H and 13 C NMR and their purity was confirmed by GC/MS analysis. All new compounds were fully characterized by 1 H and 13 C NMR, IR and elemental analysis. THF and dioxane were distilled under nitrogen from sodium benzophenone ketyl. Tert-butanol was distilled from sodium before use. CH 2 Cl 2 was distilled under nitrogen from CaH 2. Sodium hydride (65% in mineral oil) was used after two washings with THF under nitrogen. Aryl halides were purchased from commercial sources and were used without further purification. Amines were purchased from commercial sources and were distilled or passed through alumina before use. Nickel(II) acetylacetonate and titanium (IV) chloride were used as received. S4 General Procedure for the Amination of 1-chloronaphthalene using Secondary Cyclic Amines. A 50 mL Schlenk tube was loaded with degreased NaH (16 mmol), Ni(acac) 2 (0.5 mmol, 5 mol%), SIPr.HCl (0.5 mmol, 5 mol%) and 6 mL of dioxane and the mixture was heated to reflux. A solution of t-BuOH (15 mmol) in 3 mL of dioxane was then added dropwise followed by the amine (15 mmol), and the mixture was further stirred for ½ h. A solution of 1-chloronaphthalene (10 mmol) in 3 mL dioxane was then added and the reaction was monitored by GC. After complete consumption of the aryl chloride, the mixture was cooled to room temperature and adsorbed onto silica gel. The crude reaction mixture was purified by silica gel chromatography.
Angewandte Chemie, 1988
The Intersecting-State Model (ISM) is used to calculated the absolute rate constants of self-exchange electron-transfer reactions (ET) of organic species. The systems studied include aromatic hydrocarbons, quinones, nitrobenzene, aromatic nitriles, tetracyanoethylene, aromatic amines, and alkylhydrazines. Ali of the calculated rates are within one order of magnitude of the experimental ones, and the correlation coefficient between the two sets is 0.96. An electron-tunneling model has been developed to calculate distance-dependent nonadiabatic factors of intramolecular ET. This model can be used with ISM to calculate intramolecular ET rates. The system biphenylyl-spacer-naphthyl in tetrahydrofuran, whose distance-dependent intramolecular rates were measured by Closs and Miller, was used to test our calculations, because its ET rates can be calculated without adjustable parameters. Our absolute rate calculations are in an order-of-magnitude agreement with the experimental ones.
The photochemical reaction between 1-naphthalenecarbonitrile and some arylalkenes
Journal of Photochemistry and Photobiology A: Chemistry, 1991
Irradiation of I-naphthalenecarbonitrile (NN) and l-phenylcyclohexene (la), l-phenylcyclopentene (lb) or styrene (lc) or in apolar solvents leads to the formation of regioisomeric endo cyclobutane adducts and azabutadienes, resulting from the rearrangement of azetines formed in the primary step. In methanol and methanol-acetonitrile, both P-methoxyethylbenzenes and 1:l:l NN-alkene-methanol adducts (mixture of isomers) are formed. All of these processes occur with quantum yields of 0.05 or less. The effect of donor and methanol concentration, and of the addition of salts and 1,3-cyclohexadiene (no "triplex" Diels-Alder reaction), are used to investigate the mechanism. The main intermediate is a polar exciplex, or radical ion pair, the main fate of which is decay by back electron transfer.