652. Hydrogen transfer. Part XVI. Dihydrides of nitrogenous heterocycles as hydrogen donors

Braude, E. A.; Hannah, John; Linstead, R. P.

doi:10.1039/jr9600003249

Cited by 43 publications

(25 citation statements)

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“…In this case, 9 was consumed at an appreciable rate, even in the absence of [18]crown-6. To characterise 10 Scheme 1. and 11, we prepared these compounds by known routes [13,14] and completely assigned their 1 H and 13 C NMR spectra. When 12 was generated in the absence of activated olefins, the acetal 13 resulted with high efficiency.…”

Section: Resultsmentioning

confidence: 99%

“…1-Methyl-1,2-dihydroquinoline (10): The original procedure [13] was modified to resemble the preparation of 9. Thus from 1-methylquinolinium iodide (3.00 g, 11.1 mmol), the product 10 (1.22g, 76 %) was obtained as a yellow oil, which was sensitive to air, but could be stored without decomposing at À 30 8C under nitrogen.…”

Section: Treatment Of 1-methylquinolinium Iodide With Kotbumentioning

confidence: 99%

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Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Schöneboom

Groetsch

Christl

et al. 2003

Chemistry A European J

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Treatment of a solution of 3-bromo-1-methyl-1,2-dihydroquinoline (9) and [18]crown-6 in furan or styrene with KOtBu followed by hydrolysis afforded a mixture of 1-methyl-1,2-dihydroquinoline (10) and 1-methyl-2-quinolone (11). If the reaction was performed in [D(8)]THF and the mixture was immediately analysed by NMR spectroscopy, 2-tert-butoxy-1-methyl-1,2-dihydroquinoline (17) was shown to be the precursor of 10 and 11. The structure of 17 is evidence for the title cycloallene 7, which arises from 9 by beta elimination of hydrogen bromide and is trapped by KOtBu to give 17 so fast that cycloadditions of 7 with furan or styrene cannot compete. Since this reactivity is unusual compared to the large majority of the known six-membered cyclic allenes, we performed quantum-chemical calculations on 8, which is the parent compound of 7, and the corresponding isopyridine 6 to assess the electronic nature of these species. The ground state of 6 was no longer an allene (6 a) but the zwitterion 6 b. In the case of 8, the allene structure 8 a is more stable than the zwitterionic form 8 b by only approximately 1 kcal mol(-1). These results suggest a high reactivity of 6 and 8 towards nucleophiles and explains the behaviour of 7. In addition to the ground states, the low-lying excited states of 6 and 8 were considered, which are represented by the diradicals 6 c and 8 c and, as singlets, lie above 6 b and 8 a by 19.1-24.8 and 14.4-17.7 kcal mol(-1), respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Treatment Of 1-methylquinolinium Iodide With Kotbumentioning

confidence: 99%

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Schöneboom

Groetsch

Christl

et al. 2003

Chemistry A European J

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“…Lithium aluminum hydride also reduces both the I-methylquinolinium cation (20,30) work) cleanly at C-2. Reduction of 3-W-1-methylquinolinium cations (W = CONH,, CO?CH,, or CN) with triethylammonium formate gives the 1,4-dihydro derivatives (24, 3 1, 48) which are also expected to be the thermodynamically more stable dihydro isomers.…”

Section: Reaction Productsmentioning

confidence: 99%

Kinetics of the reduction of 1-methylquinolinium cations by 1-benzyl-1,4-dihydronicotinamide

Bunting¹,

Fitzgerald²

1985

Can. J. Chem.

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. Can. J . Chem. 63, 655 ( 1985). The reduction of a series of 3-W-1-methylquinolinium cations (I: W = H, Br, CONH?, C02CH3, CN, NO2) by I-benzyl-I ,4-dihydronicotinamide has been investigated. In all cases the kinetically controlled product from these reactions is the appropriate 3-W-I ,4-dihydro-I-methylquinoline. Only for W = Br is any significant amount of the 1,2-dihydro isomer obtained (15% in this case). This kinetic preference for C-4 attack over C-2 attack in dihydronicotinamide reductions contrasts with the kinetically preferred attack at C-2 by hydroxide ion and in borohydride reductions. Rates of reduction were measured for each 1 and also 1,2-dimethyl-and I ,4-dimethylquinolinium cations in 20% CH7CN -80% H20, ionic strength I .O at 25OC, under pseudo-first-order conditions. Kinetic saturation due to nonproductive I : I complex formation was observed for several cations at high concentrations (>O. 1 M). Second-order rate constants (ky) were evaluated for each W, and also kinetic isotope effects from second-order rate constants (ky) for reduction by I-benzyl-4.4-dideutcrio-1.4-dihydronicotinamide. Second-order rate constants are correlated with a,,-for W with p = 4.5, and are also closely correlated with pKu+ for pseudobase formation at C-4 of these quinolinium cations by: log ky = -0.56 pKI1+ + 7.3. Values of ky/ky vs. pKR+ describe a Westheimcr curve reaching a maximum of 5.8 for W = Br and falling to 1.5 for W = NO2 and 4.2 for W = H. These data are consistent with an intrinsic barrier of 2.9 2 0.5 kcal/mol for hydride transfer between this I ,4-dihydronicotinamide and quinolinium cations. However, quinolinium cations display a dramatically enhanced rate of dihydronicotinamide reduction relative to hydroxide ion attack when compared with isoquinolinium cations. This observation, and the predominance of C-4 rather than C-2 reduction, suggests that these reactions may not be simple one-step hydridc transfer processes. JOHN W. BUNTING et NORMAN P. FITZGERALD. Can. J. Chcm. 63, 655 (1985).On a CtudiC la rCaction de reduction d'une sCrie d'ions W-3 mCthyl-I quinolinium (W = H, Br, CONHZ, C02CH7, CN et NO2) par la benzyl-l dihydro-1,4 nicotinamide. Dans tous les cas, le produit de contrble cinktique dc ces rCactions cst la W-3 dihydro-1.4 methyl-l quinolCine appropriCe. Ce n'est que dans le cas ou W = Br quc I'on obtient dcs quantitCs significatives de I'isomCre dihydro-1,2 (15% dans ce cas). Cette prtfkrence pour une attaque en C-4 par opposition ii une attaque en C-2 lors de rCductions par la dihydronicotinamide est cn opposition avec les rCsultats obtenus lors dirCactions avec I'ion hydroxyde ou avec Ic borohydrure alors que I'attaque cinttique prtferentielle se fait en position C-2. OpCrant ii 25°C. ii une forcc ioniquc dc 1.0, sous des conditions de pseudo-premier ordre et dans des solutions contenant 20% de CH3CN et 80% de HzO, on a mesurt les vitesses de rCduction de tous les ions 1 ainsi que celles des cations dimCthyl-1,2 ainsi que dimCthy1-l,4 quinolinium. Dans les cas de plusieurs cations, ii...

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“…We in turn drew inspiration from the synthesis of quinoline heterocycles via the aza-Diels-Alder (Povarov) reaction [38][39][40][41][42][43][44] and pictured the construction of the benzoquinoline subunits from alkyne-and aldimine-modified monomers (Figure 1, right). Consequently,wepostulated that polymerization of the bifunctional monomers would furnish the desired polybenzoquinoline precursor (Figure 1, middle), which could ultimately be cyclodehydrogenated into an itrogen-doped N = 7a rmchair GNR (Figure 1, left).We began our studies by synthesizing benzoquinoline model compounds 3a,b and 5a,b via the Povarov reaction, [38][39][40][41][42][43][44] as illustrated in Scheme 1a.T op repare model compounds 3a and 3b,w ef irst formed aldimines 1a and 1b by using ak nown literature protocol.[45] We then reacted naphthyl alkyne 2 with 1a or 1b in the presence of BF 3 ·OEt 2 as the Lewis acid mediator and chloranil as the sacrificial oxidant, [46][47][48][49][50] producing benzoquinolines 3a or 3b,r espectively.N ext, to prepare model compounds 5a and 5b,w e …”

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confidence: 99%

Synthesis of Polybenzoquinolines as Precursors for Nitrogen‐Doped Graphene Nanoribbons

et al. 2015

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Graphene nanoribbons (GNRs) represent promising materials for the next generation of nanoscale electronics. However,d espite substantial progress towards the bottom-up synthesis of chemically and structurally well-defined all-carbon GNRs,s trategies for the preparation of their nitrogen-doped analogs remain at an ascent stage.T his scarce literature precedent is surprising given the established use of substitutional doping for tuning the properties of electronic materials. Herein, we report the synthesis of apreviously unknown class of polybenzoquinoline-based materials,w hichh ave potential as GNR precursors.Our scalable and facile approach employs few synthetic steps,inexpensive commercial starting materials, and straightforwardr eaction conditions.M oreover,d ue to the importance of quinoline derivatives for av ariety of applications,t he reported findings may hold implications across ad iverse range of chemical and physical disciplines.Graphene nanoribbons (GNRs), which are narrow strips of graphene featuring aq uantum confinement-induced bandgap,c onstitute ap romising class of materials for the next generation of semiconductor devices.[1-10] Theelectronic properties of GNRs are exquisitely sensitive to their width, heteroatom content, and edge character. [3][4][5] Thus,m uch research effort has been devoted to the preparation of GNRs that are structurally and chemically defined at the atomic level. [6][7][8][9][10] Although traditional top-down lithographic approaches have exhibited only limited success in this regard, [6][7][8][9][10] more recent studies have demonstrated the bottom-up preparation of pristine GNRs via the surfaceassisted [11][12][13][14][15][16][17][18][19][20][21][22] or solution-phase [23][24][25][26][27][28][29][30][31][32] synthesis of nanoribbon precursor polymers,followed by their cyclodehydrogenation. To date,these bottom-up strategies have primarily focused on all-carbon systems,w ith only al imited number of studies describing the preparation of nitrogen-containing GNR frameworks. [20-22, 31, 32] Given the immense potential of substitutional nitrogen doping for tailoring the propertieso f GNRs,the sparse literature precedent is surprising and likely arises from the challenges associated with the incorporation of heteroatoms at arbitrary locations in graphitic materials. [33,34] Herein, we describe the modular synthesis of polybenzoquinolines,which constitute ageneric class of GNR precursor polymers,and, to the best of our knowledge,have never been previously reported. We first develop general aza-DielsAlder reaction conditions for the synthesis of as eries of benzoquinoline model compounds.Subsequently,weprepare an AB-type bifunctional monomer and use the conditions validated for the model compounds to synthesize acongested polybenzoquinoline via aD iels-Alder-type polymerization reaction. [35][36][37] We in turn demonstrate the scope and modularity of our methodology by preparing polybenzoquinolines of various sizes that feature different peripheral substituents. Overa...

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652. Hydrogen transfer. Part XVI. Dihydrides of nitrogenous heterocycles as hydrogen donors

Cited by 43 publications

References 0 publications

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Kinetics of the reduction of 1-methylquinolinium cations by 1-benzyl-1,4-dihydronicotinamide

Synthesis of Polybenzoquinolines as Precursors for Nitrogen‐Doped Graphene Nanoribbons

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652. Hydrogen transfer. Part XVI. Dihydrides of nitrogenous heterocycles as hydrogen donors

Cited by 43 publications

References 0 publications

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ2‐1H‐Pyridine) and Its Benzo Derivative (3δ2‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ2‐1H‐quinoline

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ2‐1H‐Pyridine) and Its Benzo Derivative (3δ2‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ2‐1H‐quinoline

Kinetics of the reduction of 1-methylquinolinium cations by 1-benzyl-1,4-dihydronicotinamide

Synthesis of Polybenzoquinolines as Precursors for Nitrogen‐Doped Graphene Nanoribbons

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Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline